I unfortunately cannot use the key-tar type layout with my keyboard because I use a laptop. (Well, I suppose I could . . . but that would be pretty dangerous.) It looks like a lot of fun though.

Heh, no I don't think it would work for a laptop. I still might be tempted to try if it had one of those pivoting screens.

Ok, guitar style is misleading. The board needs to be VERTICAL. It can slope back towards yourself, but the thing should be aligned with your spine. Wear it like a tie? That is a very good analogy. An adjustable neck strap would be ideal. You should NOT try to wrap your palms around the sides of the board to support it. Simply place them on the key side and press toward yourself just enough to hold it there. Also, holding the keyboard in the Frets on Fire position would probably break your wrists in short order. To simplify:

YES! Except with a keyboard, not a washboard.

NO! This position doesn't even work that well for FoF, so forget typing.

I'll admit I was worried about the F row myself. Since then I have tried it out, on three different boards (IBM SK-8811, Adesso WBK-4000US, Logitech Y-RQ57). Once I figured out how to hold it, I found the F row was really not that bad. Actually, it is something of a bonus. The left thumb Shift/Backspace/Ctrl combo is delicious. Now those media keys and wrist rests, those are a problem.

While it is still uncertain if vertical is more ergonamic than desktop arrangements, where heights and tilt can be nicely adjusted, personally I find vertical is more comfortable and stable than the weird tilts, bouncing and sliding I get when lap typing piano style. Unfortunately, this is somewhat dependant on the length of your board and how deep the seat is. While sitting on a chair or the floor, vertical is fine. Sitting on a nice plush couch and a full board darn near takes my head off.

As stated before, I do recommend playing around with the keys if you want to keep it.

Unfortunately I made the mistake of 'upgrading' to a Goldtouch adjustable split keyboard very shortly after posting this layout. Biggest time waster since some idiot gave word processors 'font' capabilities. Anyways, I haven't been able to play around with any of the fun layouts since, this one included. (If anyone has been wondering why I haven't come out with any new ideas, well now you know.)

Still, lack of actual data or facts has never prevented me from having opinions before. So, while this layout is a lot of fun, I can't recommend it 'long haul' for one reaso-... two re-... several reasons.

   1) First, and most importantly, is the mouse. Unless you are lucky enough to own a trackpoint keyboard (touchpad tend to be placed below the spacebar and increase the depth of the board too much to be comfortable), this layout DRASTICALLY worsens the already poor ergonomics for switching from typing to, er, mousing(?). Depending on your setup the vertical keyboard MAY allow you to place the mouse closer to your right hand typing position than you could get otherwise, but unless you have developed a vertical mouse, switching between the two will require a 90 degree wrist rotation. That reeks of RSI. Sure, you could try working the mouse with the bottom of your hand, but I'm not sure how to avoid the 'Hulk SMASH' effect you'd get when trying to click on anything.

   2) Bad wrist angle when using the number pad and special keys. Combined with the mouse ergonomics, this makes for an awful layout if you need to do any work with spreadsheets, or databases, or number heavy coding. Correct that, any sort of coding. Or filling in online forms.

   3) Despite giving more mouse room, overall, it sucks for games. Try it. Oddly enough, this is actually the best proof I've found that vertical layouts are not easier on the body.

   4) Not all discomfort is physical. Trying to explain what you were doing with your keyboard to your boss or coworkers could be pretty awkward for everyone involved.
   

If you are still interested in messing around with it, you might want to experiment one of those flexible silicone boards. Assuming you mean a convex board instead of a board with rounded edges, shape the clarinet like frame you were describing, then glue/velcro the board down. Personally I don't think it is going to work out very well. By making a convex keyboard you are increasing finger travel distance, and making the keys slope away from your fingers is going to encourage more wrist movement. A having the board bloat at the middle might cause wrist extension as well. You might be able to avoid some of these by shifting right hand position up a row (moving the number keys to the bottom row) thereby putting both hands over the 'hump' of the curved board. On the other hand, you could try rolling the board inward and duplicate a maltron. Roll it up tight and you might even get something on par with a datahand.

So anyways, if you go through with it make sure you let us know how it works out.

EDIT: BTW, I would probably look into getting one of the keyboards pictured below instead of messing around with curve.

Back to your point though, I'd have thought some kind of low resistant rocking buttons could be a winner.  The tactile feedback of silicon boards probably wouldn't do it for me.