Having used both and having talked with reps from both companies, I can clarify:

Aqua Mira's instructions specify a five-minute wait for the two solutions to mix/oxidize and then a 15-minute treatment time.

Micorpur, as you know, states 4 hours -- period.

But if you look at AM's instructions, only bacteria is mentioned. Nothing about viruses or protozoa (e.g. crypto, giardia, etc.). AM is not EPA approved and is forbidden from mentioning effectiveness against protozoa or viruses.

In contrast, the more potent Micropur is EPA approved and is allowed to mention effectiveness against all three classes of baddies. I am not sure if it's simply the Swiss or European way of stating only the MAXIMUM treatment time, but the company rep (and various websites as well) indicated the same 15 minutes treatment time for bacteria, same for viruses, and 30 minutes for protozoa. However, the 30-minutes for protozoans (esp. harder to kill types like crypto) will need to be lengthened if water is cold -- up to 4 hours if water is just above freezing.

For me, I seldom have 4 hours to wait while hiking -- and don't want to guess the water temps to calculate whether it's 30 minutes or 60 or 90 or whatever minutes. That's why I prefer to use a combination of methods:

1. scoop water, treat with Micropur, and wait 15 minutes to 'kill' tiny bacteria and viruses.

2. suck water through Frontier Pro (2 oz.) to block out the bigger and harder to kill protozoa -- as well as improve water clarity and taste.

But strictly choosing between Micropur and AM -- Micropur is clearly superior -- quicker and easier to use.