[jtode]

The light/heavy thing definitely is noticeable on an acoustic, especially if you're fighting five other instruments, and body shape and construction has a huge influence on the overall sound; in a bluegrass parking lot scenario, there are definitely less and more appropriate guitars to be using, and the heavier the strings the better, but overall it's a question of volume, with a bit of frequency consideration in terms of where you've got the best chance of cutting through the overall din.

Your fingers are still the biggest factor.

Electric, the whole point of it was to relieve the player and the luthier of all that headache and allow them to focus on the music, negating any tonal need for large strings. It's only a factor in the sense that if you're an acoustic player most of the time you will prefer the heavier feel, but if you mostly play electric it's silly to play heavy strings, they don't bring anything extra to the mix.

Your fingers etc