To answer the OP's original question....it depends. If you want to keep SPS almost anywhere in the tank, then you're fine where you are. Registering 300 par on your sandbed can keep most SPS corals thriving, and if shaded properly can help acclimate new sps frags on the sandbed in choice places. . If your intent is a mixed reef of some acans and other LPS corals then you may be best raising the lights until you achieve a little closer to 200 across the sand bed. Sanjay Joshi (aka lighting guru) has claimed that registering 100 par on the sandbed of a tank will provide enough gradient of light throughout the tank to keep even the most light demanding of corals happy. So, mixed reef, raise them a little. All SPS and clams, right where they are or a shade lower.
My SPS tank was 27 inches high with three 400 watt Radiums on Galaxy ballasts. This was unbelievably bright. 20k my butt! Nothing other than clams was thriving on the sandbed unless I tucked it under a ledge. Even without a par meter I understood full well that SPS frags had to be tucked under ledges and slowly acclimated from the sandbed to final location over the course of a month or more. I'm having a 72x26x24 custom starphire being built right now and plan on running 250 watt Radiums on Sunlight Supply HQI ballasts with Lumenmax Elite reflectors placed 12 inches over the water. Unless someone shows me long lasting LED results with beautiful colors, I'm sticking with Radiums. . Your Lumenbrites are also very good at penetrating to the bottom of your tank with ease. I was running Lumenmax Elites which punch light down deep much like your Lumenbrites. Hope this helps.