I bought Rock Band at midnight the night it released. Since then, I noticed that my drum set didn't like it when I drummed fast. The hits simply were not recognized. It appears that other people have had this problem, but it can be most easily seen here:
http://www.youtube.com/watch?v=EAWd7nTAK0Y
Anyway, I just took my Rock Band bundle back to Wal Mart and got a new one (despite what the neon paper said to do) and when I was unpacking the drums, I noticed right away they were different. First off, the packaging was different. (Probably in a lot of ways, but I didn't take notes on my original packaging.) One noticeable difference was that in the original drum set (which will be referred to as DS1), there were small pieces of cardboard separating each drum head. That means there were three pieces of small cardboard between the red and yellow heads, yellow and blue, and blue and green heads. The second drum set (DS2) I just received didn't have those there.
The next giveaway was this: The drum sticks in DS1 had a Rock Band logo on them, and the name of the drumstick company. The sticks that came with DS2 were completely blank.
Also, it seems like DS2's stand allows the kit to be elevated a bit higher than the other one, though this isn't confirmed. Other possible differences (but completely unverified) are that the black plastic around each drum head is slightly higher on DS2, and the pedal plastic doesn't bend as easy.
The point to all of this, is DS1 was garbage and didn't work properly. It was CLEARLY a different drum set (it even sounded slightly different when the pads were hit). DS2, however, works perfectly, and handles fast hits just fine. I'm just letting everyone know, because you might have DS1 or you might have DS2, and you definitely do not want DS1.