This sounds great planning for mostly LPS but I know I will go into SPS have you tried acros in it.. But I can confirm I have talked him down to take 285 for that APX9 and a tunze chic refg light 285 plus two corals a frogspawn and a torch that hasn't been doing well for me for both of the lights I said. From what I've seen everyone loves the kessil and especially for the frag tanks. You aren't the only one using it to light the low boys. I think this just reassures me to go get it today.for this size tank, it covers the whole thing entirely with plenty of power. I am able to grow SPS, LPS, soft corals and bubbletip anemones without issue in this tank, dimensions 48x24x12 inches. For a deeper tank, shadowing can be an issue. On my display, I also have the Kessil AP9x but with an added Orphek bar for additional coverage.
$350 is a great price, I'd definitely go for that.
How is it to set up anything like the AI setting if you're familiar I hear there is plenty of in app options with the kessil as well.