Yamaha DTXpress/DTXplorer/DTXtreme

I'm considering further expansion of my DTXpress II kit.  I've added 
Pintech Dingbats on channels 9/10.  I'm considering a Zenbal cymbal 
on ch6 with removal of Ch10 (bell...or is that Ch9?) for the second 
voice of the cymbal.  

Now, I'd like to add more pads.  But how?  It was suggested to use a 
second brain.  This would be fine, since my amp has a second input 
that I can mix directly.  I use the headphone jack in my amp anyways 
while playing at home.  On stage, it comes out one place anyways 
(mono, don't have second amp).

It was also suggested to use a Trigger to MIDI converter, like a 
Roland TMC-6.  How?  I fully understand MIDI, but don't know what 
the DTXpress II brain will do with the trigger inputs other than to 
play a TONE.  I want a VOICE!!!  I guess, I can connect my laptop up 
to the MIDI like I normally do for upload/download of kits and try 
to have the software play a tone (note number).  Maybe the voice 
will come out?  I'd like snares and other voices too.  Am I limited 
to just the GM voices?  How else to connect this source?

I've found plans to build my own brain, but it's really a trigger to 
MIDI converter.  I'm an electronics engineer, so it should be easy 
for me to do, but don't know if it's worth the effort.  ALTHOUGH, 
drums are always worth the effort.  I have to watch my funds right 
now, so $210 for a TMC-6 is out of the question right now as a "just 
to try" device.

Any helpful tips?

Bill (wanting more DRUMS!!!)