I like the mule, I have had 2 or 3 of them so far. I carry all my tools, spares and snacks in the Mule (can even squeeze in a spare litre of fuel if necessary), no need for a bumbag.
Camelback bladder is the best out there in my opinion, have also tried Black Wolf, Caribee and some other cheapo camping brand, the bags were all good but the bladders not so good.
Remember ‘they’ recommend 1 litre of water per hour of exercise so a 3 litre is a must even for a half day.