AVCHD or HDV?

I've been asked to film a wedding for my Wife's best friend, and lacking the hardware I only asked for enough money in order to get the equipment necessary to get her the best possible quality. In my research the past 2 weeks I've come across a very difficult decision; do I stick with the tried and true HDV tape format? Or do I go with a newer, slightly more compressed non-tape method?

Let's round out the pros and cons (for me) of each:

HDV - Pros:

-Established
-Confident to use
-Better quality
-Can use Firewire to record/evaluate video in Adobe OnLocation in pre-production.
-Permanent backup method, store the tapes.
-Mpeg2 codec captures at 25mbps

HDV - Cons

-Tape method
-Max 63 minutes per tape
-Singular massive files per tape
-Transferring video takes as long as the video was shot
-Tape mechanisms *can* be clumsy
-Changing tapes could mean losing shots
-Deleting video means shooting over scenes
-Max resolution is 1440x1080
-Slow turnaround of shots

AVCHD - Pros:

-Flash or Hard Drive method
-Drag and drop files from camera to computer.
-Deleting videos simple as deleting a file.
-Files are by session not by tape
-AVCHD codec now captures at 25mbps
-Quick turnaround for testing shots
-Records at 1920x1080 60i and beyond

AVCHD - Cons:

-Normally no firewire port, can't use with Adobe OnLocation
-Lossy format, some artifacts
-Generally slightly lower quality than HDV
-Needs hard drive space to store (not really a con for me as I have almost 2 terabytes of space)

For the wedding I'm going to shoot, I would not like to be limited by batteries AND tapes. For practice, I've tested the time to replace batteries and continue filming to about 10 seconds, when it also takes about 30 seconds to replace a tape.

I first bought an AVCHD camera, the Canon VIXIA HG21. I was originally planning on going with the HV40 HDV camera but I decided to try this one because it had a 120gb hard drive, which means 11 hours of continuous shooting at the highest bitrate. That takes a load off my shoulders not having to deal with tapes. Even though I am confident filming this wedding, the less things I have getting in the way the better since I will be using two cameras by myself with the help of my wife.

After this wedding, I am hoping (now that we will have a 2nd unit) that we can work at more local weddings and provide two camera guys for a decent price to couples needing the best quality for their budget.

While Paul would rather not do weddings, we both agree that it would be a great 2nd income to help fund the studio. Paul would much rather be telling stories and creating film magic, I have found a nice niche doing highlight videos and creating stories out of capture moments that I feel I can apply to building some memorable wedding videos.

There's still 2 1/2 weeks until the wedding, so I can always try out the HV40. Although I'm going to try my best to make the HG21 work for me, I just don't want to deal with tapes.