Charge LR here. It does get a bit sweaty on your back but no more than any other backpack of any sort.
Lumbar reservoir is okay but doesn’t work too well when you’re getting low and need to get to the last drops. No more difficult to fill and fit than my wife’s normal Charge though.
Side pouches are handy for food etc so you can get to them without taking the thing off. The main section has more than enough room for all day rides – tubes, tools, food, packable etc