Yamaha DTXpress/DTXplorer/DTXtreme

Todd,
Here's what I have owned and my opinions:

Alesis D4 $200:  My first module!  Some nice acoustic drums sounds 
but somewhat dry and lacking on features.  No variable hi-hat and 
downright crappy cymbals.  No line-in for playing along with CD's.  
Easy to find used though.

Alesis DM5 $350:  Cleaner sounds than the D4 and better triggering 
but the sounds are VERY dry and require an external EQ like the 
Nanoverb to be bearable.  Still no variable hi-hat or cymbal choking 
capability.

Yamaha DTX2U $380:  Great module for the price (always on eBay).  
Loaded with features:  Variable hi-hat, Cymbal choking, stereo 
inputs, sequencer, Line-in, layering, EQ etc...  I really liked this 
module - it has everything.  If you're using Yamaha pads it's almost 
a no-brainer.

Roland TD8 $685:  I finally had to break the bank when I started 
using mesh heads.  The other modules I've listed took forever to get 
working right with mesh heads and even the DTX2 never really did a 
great job.  The TD8 has more features than I can list and the 
sensitivity when used with mesh heads is amazing.  Nearly as good as 
the TD10ex at half the price.

For the most bang for the buck I'd vote for the DTX2U, but I always 
regret not getting the TD8 from the start.  Keep in mind that these 
are only my opinions and your decision should be based on which 
module suits your needs and ears. Sorry to be so long-winded, hope it 
helps,
Mike