That's what I figured was going on. The slimmer fixtures with 0.5W individual lights, such as the finnex, satellite, and it looks like even beamswork now (link below) tend to have less penetration, but do a very good job evenly covering an area down to about 18 to 24 inches. Therefore, I think a slim fixture like one of these would be perfect for supplementing the two spotlights and filling in the lighting for the upper portions of the tank.
Personally, I have only used the finnex 24/7, but it does a fantastic job. I have used the 3W version of the beamswork, which does a really good job, and can penetrate quite far, but it would likely be too wide of a fixture. I don't have any experience with their newer slim 0.5W lights.
I hope this helps