Regarding having to use kb/mouse to start computer: I would enable the "allow this device to wake up my computer" feature for my gamepad and simply use sleep mode instead of power off/on. That would further minimize mouse/kb use.
It is a nice feature to be able to have available and could possibly cause me to buy some titles for the PC that I would have bought for a console without it. The Batman titles or the Lego games come to mind as examples of games that I would have bought for the PC instead of the PS3 had this feature existed. I have a nice bluetooth kb/mouse setup that I can comfortably use with a cushioned lap desk, but if I don't have to get them out to play a game I am going to use a gamepad with, that makes things that much more convenient. Guess I will get the "old" gaming rig back out and set it up on the TV again to give this a whirl. I think I already own enough "gamepad-friendly" PC games to make it worth trying.
Besides, I think the "big picture" part of the features set is a bigger deal (no pun intended) than the "gamepad friendly" part. Curious to see/use that, regardless of input device.