Yes, starboard floats so you need to secure it to your bottom glass or use rocks to accomplish the same thing. When I first put it in my tank, I only weighed it down a couple feet from each end. The ends did raise and when my MP60's went to 100% output (they're on each end too), the starboard raised ~1.5". Now, after having a bunch of rocks in, I don't have any issues. There is 3/8" perimeter bottom bracing around my tank, and on one end, the starboard comes flush to the bracing, so it is still raising 1/8" on that end. I haven't finalized my rock work on that side of the tank, so I'm not concerned.
I, too, think you're fine going bare bottom with or without starboard. In my case, I created a couple of large rock structures (~80lbs) that I needed to lower into my tank, which is 30" deep. I was concerned that one slip while putting it in could leave me with a flooded house, so I opted for the starboard.