Depends on what you're keeping and how high you're running the pumps at. I have the same return pump on my 47G and its mainly to push water from sump back to tank, and not for circulation. I run a couple of MP10wES which at max is a bit stronger than the RW-4s. I run them at 80% on reefcrest random and that's about as high as I can go before the sand gets pushed in the front of the tank (both are mounted on the back walls). No issues with the SPS so far and I'll upgrade to stronger pumps or add more once the SPS gets larger.
As for lighting, you can use your SPS as an indicator of light needed. Not enough and they'll brown out on you. Too much and you'll get bleaching. There are other factors but as far as light goes, that's basically the gist of it.
Got any pics of what the SPS looks like that are unhappy? You getting any burnt tips with them? Looking at your parameters, I would consider running the tank with a lower alk value, closer to 8 or so instead of the 9-10 that you're currently at. BTW, didn't see you mention anything about dosing. Are you dosing at all or relying on the weekly water changes to keep up with the demand?