I prefer the extended ...just easier to see what's in the gun ...
Balistically - I doubt there is much of a difference.
I tend to carry 8 chokes with me for an Over Under .... 6 chokes with me and 2 in the gun. When I start out on a course - I put Mod / Mod into my gun ...but I carry a pair of Skeet, a pair of IC, an Imp Mod and a Full .../ but OneOunce is right, I will shoot Mod/Mod 90% of the time ...with 1oz of 8's in a 12 ga at 1225 fps.
for a single barrel gun like the 390 ....I would start with a Mod ...and carry a Cyclinder or Skeet, an IC and an Imp Mod and Full ...( which is what I carry for my Benelli Super Sport).
I don't want to get on a course and find the course setter --- has put a real long target out there ...or some real close pairs ...and not have the chokes I need. Yes, they're $ 50 apiece or so ...but I carry what I consider to be a full set.