Bulbs appear to be 10"-12" off the water - true?
Nice!
Assuming you were running a single Orbit Pro before, a dual-strip Orbit IC setup would probably be more comparable to what you're running now. It would cover a lot more of the top and provide much wider coverage. Two strips would definitely be required. And honestly, if you added a second Orbit Pro, it would have been a lot more similar as well. You'd have them dialed back a bit though.
"Coverage" starts at the emitters, and more emitters over more of the tank's surface area will always be better. Your present fixture has lights from front to back and side to side – "full up".
I suspect peak intensity at your water surface (probably around 600 PAR) hasn't changed much, (assuming you had a standard setup with the tank full and the Orbit Pro sitting on the tank) but the area covered by that 600 PAR has increased tremendously.
And the way the light is spread out now vs then is much different as well....this is a big reason why the tank "looks" brighter. More light is leaving the tank. Lux/PAR surface measurements don't reveal this, but it's obvious. And you can still measure the difference with your meter. The tight lenses on the Orbit Pro have a lot to do with this as well.
How many watts are you running total on the current system?