I use RingtoneStudio (I think that's what it's called...) It let's you edit the song right on your phone, then save the smaller section, and while saving it as a new file, it'll prompt you as to what you want to set it as, if anything. Damn handy.
I've never had a problem with tones sticking on a reboot. If you are/do, it could be a system cache issue, and you may want to try clearing the data/cache in CWM Recovery before rebooting into your ROM. Then when inside, set the tone, and have someone call you and after THAT try restarting the phone, and seeing if it sticks...
If it doesn't, it's most definitely something that's buggy with your software.
At that point try using a different ROM in the ATR Thread, and if that Still doesn't work with the combined method of cache deleting, I'd suggest returning it to Metro for another. You've got a full year to do so at no cost.
After the first year of ownership you're required to have the external warranty.
