Gap as in open space or they dont quite have the same diameter? If the "skirt" of the choke tube is the end of the choke facing the receiver, action etc then yes there is a visible gap where the inside of the choke "skirt" is opened up wider than the barrel to insure the wad does not hang on anything.
The super sport is easy to maintain cleaning is easy and it doesnt have to be cleaned near as often as other semi autos. I have never seen one jam and i have seen thousands of rounds go through them because two people on my trap squad shoot them. They are very nice guns.
No it does not have comfortech with the steady grip stock if its a SBE2 than the camo pattern is probably realtree APG, if its a SBE1 it is probably advantage timber.
I have a friend with a Franchi O/U and I am not sure if its the same model as you are talking about but it seems to kick a lot harder than it should. Regardless it's a nice shotgun I think you will like it. Put a limbsaver recoil pad on it and your shoulder should be good.
I can assure you my M2 has the same problem. It isn't as bad as your description but you have to push the shells pretty hard compared to your average shotgun.
You should be able to tell if it is closed or not, close it slowly and you can tell it is not closed all the way. You should be able to load it as quiet as an 870.