I own a few small M-audio keyboard controllers that I use via USB with my laptop and have never had a problem. In the FWIW department, I usually end up sticking it in the side pouch of my laptop as I'm racing out the door when traveling or back and forth between home and work. Mine is going on 3 years old without a blink. I'm generally only using it for keyboard input into Finale for writing and arranging, but it definitely has been used quite a bit.

I played around with my friend's M-audio Keystation 88es, last night, and was very impressed with the semi-weighted keys. It really was a nice rig, especially for the price. The biggest drawback is the width. That's just too big to station at my desk.
I'm considering the keystation 61es, now, assuming that the keys feel the same on both sizes. At 39" wide, it's more palatable, although still a bit wider then my preference is.
I think the Alesis is just synth-action keys, so I'm getting less interested in it.
The Cme is listed as semi-weighted, but I wonder how it feels. I don't know any real stores that carry it (at least not around Branson). I do like that it's only 29" wide, though. It's a few inches narrower than the other 49's.
I'm starting to lean away from the Akai, as well. I really like the size, but I doubt that I'll really take it anywhere (at least not more than once or twice).
JJ