For switching to a backup pool support: just using the -f flag to set priorities as described in the FAQ works just fine for me. I don't particularly want to do something elaborate unless there's a convincing case. If people can't figure out how to use the -f flag then that's actually a documentation bug and I should fix that 
First of all, I would like to thank you for putting so much work into this. Thank you!
On the issue of backup pool support, I would love if it was implemented into the GUI. I know how to use the -f flags, but while that technique works, it's far from perfect. Some of the issues are:
- If I set one priority really high and another priority really low, there's still a few (fractions of) MH going into the low-priority pool. These MH are wasted. If I want to be really safe and use a chain of five or so pools, this waste grows even bigger.
- If the primary pool fails and the low priority pool kicks in, it still won't receive the same amount of MH as the primary pool did. Since the low priority pool has a lower priority not only in regards to the other pool but also to the whole operating system, the speed goes down a bit.