Let's see.....
2x250w=500w mh light / 50g = 10w/Gal
Yeah, I'd say you'll be just fine to grow anything.
However, I will say that you may have problems with certain corals with that much light. I wouldn't run 10K lights. That's what I have and I believe it is causing issues with certain LPS corals. But, my softies and SPS are growing like MAD!