I vote for the larger one. If it's a tie or close, it should go to the larger one cuz the folks that prefer the larger one have more to loose than those that prefer the smaller one. (Yes, I'm a bit biased)
Here's my reasoning though:
The people that prefer the smaller version simply don't need or use tap tempo at all or much and if asked, will simply prefer the smaller one. I would too if I had no use for it. Why would anyone want something to be any larger than suits their needs? When asked of, course, they'll give an opinion for smaller. However, they likely won't be pissed or inconvenienced if the larger one is chosen. At the proposed dimensions of even the larger design (wasn't it 16.5 x 7.5 inches? ), this thing will be smaller than what most people are currently using to control their KPC's. In other words, it's not like they are going to be like "This controller is so massive but I have no other choice." In fact if Chris had simply released the larger one without coming to us first, I doubt that there would be many folks grumbling about it being too big.
However, the people that want the larger one are folks that have a true need for an ergonomic tap tempo. I'm always amazed with the number of controllers with the tap tempo moved to a second row. Other than bank buttons, it's the only button that you're ever going to hit more than once in a row, often in the middle of a song if the drummer speeds up. It's quite difficult to do when playing and singing into a mic, now add standing on one foot and reaching over the first row to tap multiple times. On the front row, you can keep your heel on the ground and tap. At least bank buttons aren't usually needed in the middle of a song, assuming you organize your presets well. Those that want the larger are folks that have a genuine NEED for ergonomic tap tempo. It will be a major inconvenience if the smaller one is chosen. In fact, I might not buy it, but stick with my Rocktron midi mate.