I was facing this same decision a few months ago. I WANTED to go with a HDD based cam for the supposed "convenience" of not having to use tapes. (Previously owned a 5 year old Sony MiniDV cam).
Long story short, I bought a HDD based cam for a Disney vacation back in August. I now regret that decision immensely and have since picked up a Canon HV20 and am extremely happy! To tell you how much I wanted a HDD based cam, I also owned a Canon HG10 for a short time. Great cam, great video, but here is what I found:
1. I never realized just how much hard drive space EDITABLE AVCHD video consumes. I was honestly trying to picture how I was going to store the next 5 years worth of video. Reason number one I decided to stick with tape. Instant archive, and HDV is very easy to edit on any machine not set for the junk pile yet.
2. I thought with a HDD cam I would not have to capture in "real time". Well, that's true, if all you want to do is copy the files to a comp. To actually do anything with them, you need to get them into a program like iMovie\FCP which will not allow you to edit the native files. They have to be converted first. This takes as long, if not longer, than simply capture the video off of a tape in the first place.
3. Tape is cheap, and very easy to store either off site, or in a fireproof box. It's also your master copy, that will probably out last you as far as age goes.
Anway, I know those seem like simple things, but they are what led me back to tape, and a Canon HV20, after quite a few months of experimentation. The HV20 is simply an amazing cam, which produces unreal quality very easily. Also, while I can only burn SD DVD's at the moment, the quality of them, after being shot with the HV20 is also amazing. Even when making a DVD, I capture in full HDV\1080i and keep it that way all the way to the end. This seems to get me nearly studio quality DVD's by the time they are burned, even if they are still in standard def.