Yamaha DTXpress/DTXplorer/DTXtreme

Hi Guys i know this isnt really related but i have been offered a 
Alesis DM5 module at a low low price so low that it is cheaper than 
it would cost to buy a triggering device like the roland and kiti, So 
that i can expand my DTX2 kit with more pads and cymbals.
First off is the Alesis compatable with the Yamaha pads ?
Secondly what would be the best way to link the two modules 
together ,I presuming a mixer of some kind but suggestions would be 
much appreciated.
Finally i know we all love our DTX's but is the Alesis any good and 
could this be the answer to my quest for ultimate e-drum heaven?

As always thanxs in advance,
Lee.