Nice, these work great already :) Yeah, the jumping is different from its sequel Rampage Edition. You take damage from jumping/falling from too much of a distance, sliding down (some?) slopes, etc. Also you die when falling too high a distance, before even hitting the ground :P That's probably what you meant by having problems.
Codes are fine the way they are, though I wonder if any exploration is possible by making Grant jump even higher. About landing without doing any damage, could this just be fixed by having already existing invincibility codes activated, or is health handled differently here? I am using 2 codes for invincibility, one of which refills health upon gaining damage.
The Raptor probably doesn't need jump higher codes. If you press/hold up and jump, its jump is already insanely high. You might break the game :P Hm, checking Gamehacking.org, it seems that I'm using USA codes. I guess USA codes also work on the PAL version? I'll have to double-check.