I've settled on the PX4 as my carry gun, and have drunk the P-F kool-aid on having multiples - I've got two that are decock-only and one that's DAO. My "small" gun is also TDA, a Walther P99C. I've taken classes with both.
I started with 1911s and later branched off into revolvers and still enjoy (and occasionally carry) them. I also just got my M&P45 1.0 back from S&W with its dead trigger revivified - they replaced the trigger and it's much improved.
I'm taking a class at the beginning of February and am seriously considering running the M&P45. It's the thumb safety version and I treat it like a 1911. I'd bring my Series 70 Combat Commander as a backup in the unlikely event the M&P goes down...or maybe reverse the roles, since the Commander hasn't been getting much love since I got the M&P ten years ago.
I'm more serious than I've ever been about improving my defensive shooting skills. I realize that keeping with one gun exclusively is the best way to do this (in terms of hardware). I think that "keeping my hand in" with other platforms isn't a bad idea, but I'm interested in other's opinions on this. An okay idea, or am I gonna get killt in da streetz?