it looks like the touch dual is comparable to the CDMA touch in terms of specs and has more ram and processor speed than the GSM touch. i found spec sheets from HTC:
Touch Dual:
http://www.htc.com/www/product.aspx?id=316
Touch:
http://www.htc.com/www/product.aspx?id=362
and yeah, I think Bell is moving in the wrong direction, if they do get the Dual I hope it's short lived for their sake because as soon as the Diamond and Pro launch the Dual (and all other predecessors) will be history