While i don't have any scientific measurements my gut feel tells that 5.24 firmware somehow depletes the battery faster - i noticed my battery level going down quite fast on 5.24.
Yeah, initially my battery usage was high, around 8% per hour of cycling, up from around 4%.
After a handful of cycles, it's come back into the normal ballpark... I'm going to give it some more time and see.
A easy battery logging function I'm using is that found in the IQ Data screen, MY EDGE2. I have it loaded to a Data Screen but have said data screen disabled. The result is my Activities still have a battery logging graph. This makes it easy to monitor average battery consumption over several rides