Reguardless of what Sony Techs tell you [and I talked to a couple of them] their Steady Sure Shot stabilizer IS physical and not DIGITAL. Optical floats the lens in a movable contraption and is better for everything EXCEPT mounting it to a vibrating piece of machinery - it just becomes a jittery blur and there is no way to shut off it's physical mounting. Mounting to my helmet [foam and duct tape - don't ask!] cuts vibration AND jarring quite a bit and should be usable. I have not done this with the HV20 yet, but have with my other cam. Works great.
Yes, TAPE is better for a vibratey filming, but the Optical Stabilizer wrecks that option. I use STANDARD MiniDV tape, not the special over priced HD DV tapes. They have not had any problems that I notice, and I did a bunhc of research before going down that path. I suspect the HD tapes are of better quality tape-wise, but it's digital: either works or it don't and the regular tapes work. Walmart seems to have the best price on MiniDV for walkin. I bet online is cheaper somewhere. You can't go wrong in HD. Crap looks INCREDIBLE!
http://www.camcorderinfo.com/
has lots of info and helped me make my decision to purchase the HV20
I assume you have HD TV? I have a 50" plasma that does 720P native, STILL looks incredible. I can only imagine it at 1080i
Only drawback I can think of is HD related, not HV20 related: you can't burn HD DVD's yoruself without extra expense, and you can't really share them with friends who dont have HD!!! but you can ALWAYS scale stuff back to regular DVD for burning - so consider what you want to accomplish before jumping onto HD recording
one more thing: I did not wait for 3 chips HD, it might be out now. That would be even better, but more expensive also I bet