I use a drafter, personally i think its the perfect size, slightly bigger than a Mule with more internal pockets for things, dedicated pump pocket etc..
Hydration pack wise its superb, no problems with it at all. Bite valve works well, click fit connections etc…
My only small annoyance is the fact you have to undo the helmet carrying straps to get into the bag properly. Nothing major but they should have put the straps onto the front of the bag not onto the back side of the zip.
Its been out in all kinds of weather and kept everything dry, including my phone in the phone pocket on the outside.