Yes, I'm actually splitting the single source 3 ways: 2 for the 75g, and one for a 10g. I'm using some (2) Y-valves I picked up at a local welding supply shop. They have needle valves for each output, but aren't as accurate as I'd like. It takes a long time to get them set right. Adjust one, and it changes the pressure on the others (I think this is a problem with all "gang" valves). I've finally got it dialed in right. I use the regulator pressure valve for "global" modifications. It's kind of ghetto, but it works. Currently, it's working really well.
As an update to the thread, I've found that the spraybar approach lacks when used behind a dense background. If there is some break-up in the background planting, then it should be fine. Also, I think in long tanks (>48"), this method would be ideal.
I currently diffuse CO2 into my Eheim 2028 cannister and into a strong powerhead for the mist effect and extra circulation.