I don't think that you can call Flow bindings as "real step ins". The working principle is so different compared to Burtons SI or K2 clickers. Flows are somewhere between strap and step in bindings - the real advantage is that you can use whatever boots do you like.
I have used Flows for kitesnowboarding and on slopes, they are really
great and easy to use compared to at least straps- very solid feel and
those are quite stiff, easy to put on, but realeasing a boot from a
binding is sometimes a little bit tricky. But overall, a highly recommended
alternative for straps and surely you don't have troubles to put them on
on a deeps snow. It seems that Burton SIs and clickers have problems with powder or icy conditions as far as I have heard.