That's great Hoppy! You should hear if the CO2 thing works by the faint noise of bubbles being smashed to mist in the impeller. I like the audible feedback... Once or twice the silence was an indicator that something didn't work right in my tanks (Plus if there is some serious overdosing I would hear that too!).
Did you route the CO2 line through the sponge? I avoided that because of maintenance concerns, didn't want to have to take the whole apparatus out of the water you clean the sponge.
How does the MaxiJet work when turned on its head? I had a MaxiJet 600 (I think it was a 600) a while ago and I returned it because it vibrated and was very loud. Might have just been the one I got.