I am planning to use 50W MR16s in my kitchen. I'm going to use 3"
housings, but I can't decide between line voltage and low voltage. MR16
comes in both 12V and 120V (GU10 based) bulbs. What is the difference?
Is GU10 MR16 hotter, less brighter, etc?

Even though the line voltage setup is much simpler (no transformer, no
more expensive low voltage magnetic dimmer), the low voltage fixtures
with MR16s seem to be much more popular than the line voltage versions.
Any reason? I was talking to a salesperson today, and he told me that
they hardly sell 3" line voltage housings.

Right now I have access to the ceiling, so I can use either new
construction housings or remodeling housings. However, once the drywall
is put up there, I won't have any more access. Even though I prefer the
new construction fixtures, should I go for the remodeling ones in case
I need to replace a transformer, etc. (assuming I end up getting the
low voltage housings)?

Thanks,
Matt