when Honda took over the montesa marque, part of deal was to always produce a trials bike, and thats what they have done. They have kept costs down, got it more or less right on the drawing board and its proved time and time again to be a winning formular.
Why do you need more power, does the bike not produce enough? Is flat out in third too soft for you? I have not come up against anything that a 250 will not go up. Alot of riders seem to be under the misconception that more power makes them a better rider. wrong. More power can mean more problems to deal with
An underpowered bike will bring the best out of your riding. If you can make a 125 go vertically up 6ft without a kicker then your going to get on a 250 and it will feel like a main road.