Further to last night's discussion: I always RAID1 swap when I do RAID1 setups. If you don't RAID your swap, and 1 disk dies, and any swap space is being used, then your system *will* crash when it next does a page-in from swap. It may even crash on the next page-out.
RAID1 on swap increases your uptime and survivability substantially.
If all you care about is data integrity and don't care about uptime and a crash/reboot cycle (ie: a simple home machine), then yes, not raiding swap would be acceptable. You would gain a performance advantage.