Yeah, filters have a "limited" life. But then again, so do MP1 tablets. And I gaurantee you'll get more use out of 1 filter than 1 pill. And probably better price. I don't think I've ever "out drank" a filter yet. And if you do, you swap filters.

I think the 4 hours is only for really dirty water - read the instructions, I think it might be OK after 2. Which means you'll likely need 2 bottles, one working, one to drink from. I assume you'll have plenty of water to access, so you can fill as you go. Where I camped, in CA, it was "thank God there's water at this creek! Everyone top off!"

Same thing though - slosh the clean water onto the threads. Done this for years with no problems.

Personally, I'm a filter guy. Pills are a distant second... or even third, if I boil water.