Avast there matey,
You can have one trigger formulate two sounds, but you need two modules to accomplish it. I use a TD-20 and a Korg Triton Rack to accomplish this feat, although I find I have rare need of it.
As far as cross fades, it takes incredible finger control to get precise cross fades, regardless of the module used. I know of only a handful that can consistently acheive that level of control (you may just be one for all I know). However, the drawbacks and limitations of the TD-20 will make it harder. I personally have two adjacents pads set up, one for snare and one for rim. That way I can strike either one individually, or both simultaneously to achieve a combination sound (but that does take both trigger pads to accomplish).
Hope this helps.
Fair Winds and following seas,