Hoppy's chart seems to say that at 25", going from 2 bulbs to 4 on the Catalina fixture increased the PAR by about 70%.
If the same is true for the Ray 2, then having two fixtures on would result in a PAR of 85. Would that be excessive for 4 or so hour bursts?
Either way, it sounding like I definitely won't need more than two fixtures, unless I'm trying to grow coral in my freshwater planted aquarium. So between the lack of bulb replacements and the lower energy consumption, the LED fixture is sounding good.