The 4 bulb would give you more intensity than the 2 bulb would which would allow it to support a wider range of coral over the 2 bulb fixture. If you do go with the 2 bulb fixture, you might want to place coral further up in the tank and stay with soft coral, and maybe some LPS
. I would even consider going with a 150w or possibly a 250w metal halide fixture. Zer0 who is a member on here got a 150w halide pendant from fishneedit.com and seems satisfied with it, they also have cheapest prices on a halide fixture that I have seen. Hope this helps, and welcome to AA!