In reply to Oujmik:
I take a very similar approach - fell shoes for almost everything short of graded snow routes....
However, I got talked into stiff boots (b2) for a grade 4 scramble (not sure when they were invented!) recently, and they certainly let you stand confidently on small holds in a way that flexible shoes don't. I'm sure it would have gone in fell shoes, but in a rather different style - more smearing and less standing on small bits.
I suspect boots also win on less well used routes - possibly better at coping with dirty, slimey, vegetated rock?