I am pretty comfortable using the SNES default for dashing. I used it for years after all. However, I have to admit that the Megaman Zero/ZX control scheme is really nice, though I have always used L to dash, rather than R. The R button is for alternate attacks.
The only time I ever messed with the controls for an X game is when I play the Gamecube version of the Mega Man X Collection. The default button mapping is very problematic in the Gamecube versions of both the X Collection and the Anniversary Collection. I mean, the funny button layout of the Gamecube controller means that it is possible to do a dash jump while charging using nothing but the face buttons, but you have to make sure nothing important is mapped to the B button.
Anyways, did anyone ever use the default "hold R then press B" method of using secondary weapons in the Zero games? I always immediately switched to the "just tap R" control scheme. For that matter, did you people prefer putting the gun or saber to B? I always went with Buster assigned to B and Saber assigned to R.