I just shoot skeet and sporting clays.
I ordered the field version by accident. I shoot a 32" 686 with extended extreme chokes for sporting and just ordered another 686 sporting 30" I'll run flush chokes for skeet. Wanted the same gun with a shorter barrel so mount and everything was the same. I've been having a lot of trouble on the last station on skeet after initially switching from a 30" Barrell to a 32", like shooting 21 to 22 til I got to the last station.
I borrowed my buddies 30" last weekend and was doing just fine on that station with it.
If I was big into trap, which I've never shot, it seems most people choose 32 to 34" barrels with a high rib.