The Alesis M1's have a slight rise around 16KHz but in their price range, they have just about the most acurate low end I've heard.
That rise in the highs is also what I've noticed. To my hearing that low end is too much. To me it's a bit muddy and Hi-Fi. But hey, I'm used to mixing with Yamaha NS10's so any speaker has too much low end for me

I like the KRK V8's a lot (thankfully, the Yamaha's aren't the only speakers I use), but they are in a totally different price range.
Key velocity is touch sensitivity. That means, that the keyboard responds to the velocity/speed/power at which you strike the keys (soft, loud, etc).