Hi Martin,
Panasonic have announced upgraded
"A" versions of the AC130 / AC160 cameras, this upgrade can also be purchased by current owners of these cameras for $300.
Panasonic Introduces Upgrades to AG-AC160A and AG-AC130A, Newest Generation of AVCCAM HD Handheld Camcorders
The main features of this upgrade are "expanded focus assist" and "turbo speed one-push auto focus function". If you plan on shooting stage productions, I would definitely wait to buy the upgraded camera.
That said, I have shot a few theatre productions with my Panasonic HMC-150 camera using manual focus, and had little trouble keeping focus as I zoomed and panned across the stage. ( anticipating the actors movements has always been trickier for me, unless I've seen the performance a couple of times )
These newer Panasonic AC130/AC160 cameras, are much sharper than my HMC-150, which is more of a 720 HD camera than a true 1080 HD.
If you don't want to go Panasonic then the other option to consider is a new or used Sony EX-1R which is very sharp, great in low-light, with a good autofocus system. The main drawbacks with the EX-1R are a shorter zoom range, a more expensive camera, and a less ergonomic camera. ( harder to hand hold )
You might even consider renting each of these cameras if you are undecided on which to buy.
