Depends on the rom. Number of bars highlighted differs between sense and aosp I believe. Build.prop differences could also have an effect.
Battery life is a whole different issue. Again, if all things are equal (same cpu settings, apps installed, sync settings, etc) then you can compare. I've had great battery life on all the latest roms I've tried, especially since 4.3. Things like using something like tasker to handle syncing, using apps like greenify to sleep every non critical app, etc has made a big difference. I've also had good success with the latest radio and not having my connection fluctuate between lte, 3g alot.
Sent from my HTC One
HTC One XL
CleanRom DE 3.1.1