I've tried bee keeping few years. I'm no an expert but in my opinion the flow hive does not solve the real problems. you have to disturb the bees in any case whit the flow hive or or without flow hive. I think a simpler way to harvest honey out of the hive without disturbing bees at least not very violently way is use spacer between colony box and honey box. bees can go out of honey box but can no longer get back in the honey box. wait a couple of days ans honey box is free of bees. then you can harvest honey without crushing bees. at least much cheaper way to do this and I find it easier as well.
( I do not know what is the name of this device in English please help me) http://www.mesi.fi/tuotteet/mehilaispako-nicot/ or