I think you'll be fine with it. I dont think you're going to get super SPS growth down on the sandbed, but with sand there (on the bottom), you arent running the water movement at good levels for SPS anyway, so its a moot point.
If you're really concerned about it, I'd try the A350W's and if they're not enough, then add a pair of A350's for the extra punch to the bottom.
At that point, you'll have spent more than a pair of Radion's would run you...so there is that to consider.
I know this is a thread about Kessil A350's, but I have a pair of Radion's over my 120 SPS/Anemone Reef and they replaced a pair of Phoenix 14K SE's run by an HQI ballast.
I'm running them at 80% intensity level with the color setting at 12k which is very, very close to the color of the Phoenix bulbs. My H.magnifica anemones have not moved and if the intensity of the light had decreased, they would have.
One thing to note, the Kessil A350 light at 100% on both channels is bluer than the Phoenix bulbs, and looks to my eye to be closer to the coloration of a Hamilton 14K than anything else.
Nick