Personally, and as I said before, I think it's easier to broke a distro upgrading a LOT of packages in a 6-month period than upgrading it every day. OC, sometimes, when APIs/ABIs change (and that happens a lot in Linux), there's a big chance things don't go very well if you weren't warned (although in Arch Linux, their DEV's do a very nice job warning you when there are some package bumps that migh break your system)...

Furthermore, most of the package upgrades problems that exist in Arch are related for those who use the testing repo (like me), but in most cases, it's easy to upgrade the system as typing "sudo pacman -Syu"... And things don't mess up, almost in all situations.

Cheers