I can vouch for those MSR bladders. They are very sturdy, I have two 6 liters.The only problem I had was when I first got them a few years back the inside smelled really bad, I would describe it as a chemical smell. When I tasted the water, it tasted like the smell.
I followed the advice of a few kayakers who had them and fill them up with clean water and dropped a few denture cleaning tablets, the ones that fizz.
It made it much much better but I had to do it like 4 or 5 times. Then I could still taste a very faint chemical taste but it was really not bad, specially when I added electrolyte powder flavor to it, which I made a habbit of doing.
After a while the taste was gone and I thought maybe I had just gotten used to it but when a buddy tried it with some plain water he said there was no taste at all.
I'm not discouraging you to buy one, as a matter of fact Im thinking of buying another one. They are just really good bladders. Never leaked after so many years of extensive use.
FishBones