AVCHD Storage strategies

I know this is not iMovie specific, but most on these forums have some great ideas. The basic question is how most of you that have and utilize a cam with AVCHD are handling long term storage? What's your workflow? I'm asking this as I have an opportunity to purchase a Canon HG10 at a VERY appealing price due to discounts and credits that I have. I currently have a Sony hdr-sr5 which has the ability to shoot SD and HD, where the Canon ONLY shoots in HD\AVCHD. With the Sony, I shoot 80% of my stuff in SD; stuff like kids playing in yard, dogs etc. I like this option as high quality SD takes very little space.

To not ramble on, I REALLY would like to shoot everything in HD, and would be forced to if I pick up the Canon. The issue of course is with file sizes, especially once imported into iMovie.

So in a nutshell, what are some of your best strategies for dealing with these files? Disk images from RAW AVCHD footage stored on external drives and brought into iMovie as smaller footage is one of my thoughts, but even with that, I'm wondering just how quickly this could grow.

Thanks for any input or insight!