Well... not exactly Dy mar...
It has just been said that it is impossible to change player datablock traits "on the fly" without separate datablocks.
The best that can come out of this is a datablock that is slower and can jump higher, simulating a low-gravity environment.
(maybe some variations of the shielded player as well?)
If nobody replies in a day I'm locking for being a difficult subject/suggestion.
Give some new ideas!
(also, it's Hallelujah)
=P