Crosstalk refers to dial settings in the character figure being automatically picked up and emulated in the conforming clothing. It is a crude sort of autofit, assuming that all of the morphs in use are in both items.

To use or not to use?

99% of the time, I find it useful. The other 1% is a case where it seems to cause poke-through in some poses. In that case, it's a PITA.