Yamaha DTXpress/DTXplorer/DTXtreme

Hi,  I have a standard DTXpress II and wish to expand a little by adding 
cymbals.  I just wondered if anyone could give me a hand.  Can you only add 
1 extra cymbal to the module?  Can this be a YAMAHA PCY-65S Cymbal 
Pad, Dual Zone Stereo Cymbal E-DrumPad?  Could I possibly add a Yamaha 
BP-80 Bar Pad, stereo, two zones, instead?  I was told that the Bar Pad is not 
compatible with the DTXPress II (only with the mrk III) - is that right?  

Many thanks
Fiona