At 24", par on the Sat + is at 58% of what it is at 12" (21 @ 24" vs 36 @ 12")
At 24", par on the Ray 2 is at 41% of what it is at 12" (36 @ 24" vs 87 @ 12")
As you see, the Ray 2 drops off in PAR faster than the Sat + does. However, the Ray 2 still has a lot more PAR at any level. For me, the Sat + would not be enough PAR for my plants. I'd need 2 of them, and that's a pretty big price difference.
Yes the Sat+ is less light, though it can grow 90% of the plants in the hobby without a problem.
The different in the lights is the amount of led's used to achieve the rated par. The finnex uses A LOT of small led's across a board, which gives off a lot of light directly under the fixture, and diminishes very quickly. I took my own par readings of the finnex lights, and they're par claims about light at 15-18" were correct, but my graph was much different than advertised on how intense the light actually got, so the manufacterur claims i believe are skewed quite a bit. The current usa fixture, marineland, build my led, etc, all use fewer leds, but more powerful leds, more power means the par will not diminish as quickly, and par is much more progressive, similar to t5's dropoff.