Steve E wrote:

Wow I like the look of that MSR one but yikes she's pricey!

In this case, you get what you pay for. Remember: It's a purifier, not a filter. Cleanest water you can get. I've had the original MSR Guardian Purifier for two seasons now and I will never go back to any other system. Yeah the purifier is expensive and the replacement cartridges are around $250 - but it does 10,000L. Totally worth it - 1L nalgene in 30s.