Originally Posted by ericm979
Shifting from the 25t to a 30t will be problematic. The ramps are not made for that big a jump.
I've never done it, so you may very well be right, but a number of Shimano's standard mountain cassettes make a 4-tooth jump in this general range (24 to 28, 26 to 30). I would expect you'd want to lighten up the pressure when making a 5-tooth jump, but I would think it would shift OK.
But again, I've never done it. What sort of problems have you run into?