Thank you for your reply.
The td4kx drum kit is out of my price range. But I understand you what you mean by being satisfied with Roland.
It is a bit unfair to ask about the Alesis DM8 as it is not out till May. But the vids below, I like what I see on the Alesis as far as their drum heads and module. But Roland is well respected.
Let's see if this helps:
Alesis Vid an NAMM
http://www.youtube.com/watch?v=fvlZdIUKc9I
A decent TD-4K2 vid is just as tough to find as Roland seems to want to focus on the X series.
http://www.youtube.com/watch?v=lcn6RXZurkg