That's one possible solution. But there is also the danger of putting too many distractions into a listing, and thus losing customers. It's a decision that everyone must make for themselves.
In my case, I use Auctiva for listing, and have a SmugMug account for backup - which didn't help me today, as SmugMug was also knocked out by the problems at Amazon S3. So it was simply a BAD day, all around.
Like a friend of mine says, "Some days it just ain't worth gnawing through the leather straps".
Thankfully, the pics are back - and we can trust that the cause of the problem will be pinned down and corrective action taken. But there will still be the occasional bad outage - you can count on it. NO system is immune.