Since I conceal my 40C (and FS 40) in open top holsters with no thumb breaks I don't think I'd like the flap. Of course I guess you could call a covering shirt a flap because in either case you'd need to clear something away to draw the gun. I see it also comes with belt loops which to me would be better than clips.
As far as being bigger than your average holster if open carrying it & asked what it is you can tell them that's your flux modulator meter & that oughta shut them up, lol.
As far as the legality in your state goes in my opinion the gun is concealed because no part of it shows & the gun itself is not printing so it should fall under any concealed carry laws. There is nothing that says "gun" when in the case so I don't see that it could be construed as open carry. Best to check with someone in authority about that if open carry is illegal.