My tank is 3x2x2 and I am sure that one of these units would be fine for SPS - It's when it gets bigger from this point I think another would be needed for sure.
I got 2 of the other units that are not the most reliable LED units (in my opinion) and when one failed, moving the other unit to cover in the middle was not too bad.
But.... The Orphek ones certainly look more up to the job.
The price is a little off putting is you were setting up a new tank, but then if you take into account the electricity that you would save over x amount of years, they are very cost effective.