1. The vise hardware is less expensive than our other vises.
2. We don't make a twin-screw vise for bench use (face vise position).
3. The Moxon vise works sweetly.
Before I get into the topic at hand, let me say the following. This is my personal opinion regarding workholding. It applies to how I work, and the furniture I build, which I think is typical of what most people build for their homes. Rectilinear forms that are suited to typical bench holding capabilities. If you make Maloof rockers, you have very special requirements. I'm not going to attempt to cover that here. Also, I am not a businessman. I'm a woodworker who happens to run a woodworking-related business. So my opinions here will not be offered to simply bolster a product or sales. That goes against our personal ethics here. We don't make anything that we ourselves do not use enthusiastically. I'm the most active woodworker here, and I use all of our products virtually every day.
I've been working wood seriously since my first (and only) year in college. I'm not exactly old (I'll be 38 in a couple months), but I do have about 20 years of working wood under my belt (along with the results of many rounds of southern fried chicken). My first bench was a cast off beauty-salon styling station (my two uncles were hair stylists and toupee makers, and no, I was never a client.) I removed the sink and plumbing, added a particle board top and vise, and stashed my grandfather's junk tools into the drawers on each side. I kept the giant mirror for a while, until I grew tired of glancing up after a mistake and seeing the humiliation on my face. It was a good way to keep me humble. This was also about the time my physique changed from resembling Clark Gable to not resembling Clark Gable. I walked the same path most do. Trashing or re-purposing a previous ultimate bench, and building another ultimate bench. This is how I got to where I am today. I have reached the point where I am completely satisfied with my bench, for how I work, and can say confidently that I will never wonder about building an even better bench in the future. If I do build another bench for myself, it will be nearly identical to the one I'm using now, including its three essential vises.
The Wagon Vise
I eliminated my moving-block tail vise some years ago in favor of a traditional wagon vise. I have not looked back. The simplicity of the wagon vise far outweighs the frustration that typical tail vises generate. And I can work on that end of the bench, just like any other area of the bench. I don't have to worry about sagging, I don't have move a large, heavy block of wood just to move a dog, and I don't have to treat that area of the bench like a scientific instrument. Wagon vises allow robust tops. Yes, I don't have an open jaw on that vise, but I haven't found the need for one yet. There are other ways to accomplish that rare task. Would you trade short term inconvenience for long-term frustration? For planing the faces of boards (and that's what this area gets used for 99% of the time) the wagon vise is the best, period. I should clarify this paragraph by adding that when I gave up on moving-block tail vises, nobody worth their salt was making decent hardware. Lie-Nielsen does now. I stand firm though in my opinion. Wagon vises are my preference.
The Leg Vise
I've used every type of face vise out there on a bench at one time or another. The leg vise is the best. Hands down. Why? Its grabs stock tenaciously with little effort or thought. Extremely frustrating is a vise that gives zero feedback on pressure--when you crank down (and you shouldn't need to "crank down"), do you know where your effort is directed? Is it overcoming the build-in resistance of the vise mechanism? Is the screw getting tighter on its split-nut, only to pop out at the last turn? Or is it going directly into holding your board against the front edge of the bench? Leg vises provide the latter. You are moving very little weight or mechanism when adjusting a leg vise, especially if you have a weight-support system like the Glide. You know exactly when the vise starts to grip your workpiece. The geometry of the vise also provides extreme, but controlled force. In other words, you don't have to think about operating the vise. I won't discuss having to adjust a pin. It's not an issue for me or our customers. Simply put, having to reposition the pin allows great simplicity of design for the rest of the vise components, guaranteeing consistent performance. Again, would you exchange short term inconvenience for long term frustration?
The Moxon Vise
Here's where the argument for the leg vise really comes into play. With the repopularization of the Moxon vise, the twin-screw face vise becomes obsolete. Why? Twin-screw face vises excel at one task: holding boards between screws for working ends. They do not hold boards well above the screws for working edges, because the vise has no fulcrum or pivot point below the screws to balance the thickness of the stock. The vise racks every time. It can't hold work positively and securely with minimal effort. It's like using two leg vises, only you've eliminated the length advantage of the chop, and the fulcrum of the parallel guide and pin. Only when you place a board between screws, where the chop can clamp down on material equally both above and below the screws, do you get excellent workholding. So in building typical, rectilinear furniture when do we need to vertically work the ends of boards? Primarily when dovetailing or tenoning. And both of these sawing tasks are best accomplished with the workpiece in a raised position, above your planing bench height by about 6" or so. The Moxon vise raises your workpiece to this height. A twin-screw vise as a face vise forces you to bend over to dovetail or tenon, and it falls short for typical face vise tasks like planing edges of boards. In my opinion, the Moxon vise completely eliminates the need for a twin-screw face vise.
So back to the original question: will you be offering a twin-screw face vise? or can I use your Moxon hardware as a face vise in my bench?
In my opinion the utility of the twin-screw rests entirely in holding work between screws, not above, and all of that work is best accomplished 6" above bench height. So mounting a Moxon on the front of a bench is inefficient, and counterproductive. You've eliminated the best aspect of the Moxon: raising work to a proper working height and holding it there securely. Plus, the vise capacity is only 2-1/4", more than enough for end work, but perhaps not enough for face vise work. Yes, we offer longer screws, but this is in the context of using the Moxon on top of a bench for a specific, infrequent use. You would not want to keep longer screws on this vise permanently in a face vise position. The only time I would mount a Moxon permanently would be in a dedicated bench, at "Moxon height". If you have room for this dedicated "joinery" bench, by all means mount a Moxon permanently on this bench.
In the end, yes you could use our Moxon hardware to build a limited capacity face vise. I just don't think its a choice you'll ultimately be happy with. If you're looking for an economical face vise, build a leg vise with a bench screw (Lie-Nielsen makes a nice one for $85) and use our Moxon vise in its best context on top of your bench.