I think Alan summed it up really well.

I do recommend that people get the 350 instead of the 175 because the price difference is small, but EP350 to EP500 is a much bigger jump.

If you want to enjoy movies the 350 will do a great job. If you want to shake the room and scare people (or if you have a bigger room) you might want to think hard about the 500.

M60ti, VP180, QS8, M2ti, EP500, PC-Plus 20-39
M5HP, M40ti, Sierra-1
LFR1100 active, ADA1500-4 and -8