Hello bass007,
I've got a mixture of mains voltage and low voltage recessed lights in my house. I've found that the low voltage ones give a crisper, whiter light.
However, even though I've gone for quite good quality transformers, the low voltage ones to tend to fluctuate in brightness, especially when dimmed down low. I watch films with them down very low, not completely off, so this can be very distracting!
Personally I'd recommend mains voltage ones for a home cinema. I'd suggest nine 50W lights for a room that size. The cheapest supplier I've found is
Ricam, whose customer service was also very good.
Hope that helps!