I used to think 30 watts would never be enouph, man was I wrong. My AD30TC is loud as hell. I play with a fairly heavy drummer and alongside a biamped 280W bass rig and the 30W holds it's own strait up with enouph headroom to allow me to turn up a little if I need to.
On top of that the harmonics add alot so even if your volume is a bit lower than what you'd like it still stands out in the mix
with that said if volume is a big concern then maybee going for the rocker 50 would be best just to play it safe, etc. But from a personal standpoint 30 class A tube watts is deffinately enouph.
Ibanez "cimar" acoustic [1970-1975?]
Ibanez acoustic electric