Thanks everyone for all of the input. Sorry for not including the firmware versions. I actually had it in the post but must have edited it out at some point. They are a collection of firmware versions 303, 306, and 310 (all PM3 units) so nothing as old as the double digit versions that people are warning about.
I will go ahead and wait a couple more weeks for 315 then proceed with the upgrades. I appreciate everyone's tips on doing the upgrades. Looks like I'll get some rowing in too.

Thanks!