[arch-general] arch32 -> arch64 migration without reinstalling

Since I've already got a 32bit laptop, I was thinking of migrating my Core 2 Duo to arch64 (as a TU it would be really helpful for building new packages and helping the other packagers). Now, this desktop is my main system, so I'm not really happy with the idea of reinstalling and reconfiguring everything (given that, at this time, I have more than 1700 installed packages). So here's the idea: is it crazy to dump the package list, boot from a cd, change my mirrors in x86_64, change pacman's installation root to my mounted disks, reinstall the world and then check for *.pac*? Is there any risk I can't see in doing this? Thanks, Corrado