For large groups it may seem slow, but I assure you it's faster than my msr waterworks2. Our scout troop has no problems with it, and there isn't much of a lineup. Two filters, 22 scouts. Scouters have their own (mine).
I collect 1/2gal water in one bladder, hang it up and go do something else. Come back in less than five minutes and its ready to be reloaded.
In Canada we use Pristine which is the same clo2 as aquamira but a different brand name. Strong chlorine smell for a few minutes that dissipates and isn't really much worse than tap water. Certainly nowhere near as bad as a swimming pool.