Hamster the point I was getting at with manufacturers was nearly all competition shooters were shooting 28 or 30" tubes. Then 32" came along a few started scoring well with them and a new fad was born. To sell to us the run of the mill public. We wouldn't buy another 30" when we have one that works but a 32" yep need one it's the answer to get more crosses on the card. Then fully adjustable stock then comes adjustable ribs and weights for barrel and stock. Manufacturers need something to make us part with our money.
The extra length barrel for weight can be nullified by heavier barrels or chokes. If your 32" tubes weigh in at say 1600 grams and your 30" tubes the same you have no difference in weight of swing bar the length and then can you actually see it or feel it. Same as I very light 32" gun verses a very heavy 30 or 28 gun.
I'm not convinced with barrel length alone. I know most of the top boys use them, but weight where you want or need it to me is the key factor. A lighter gun is more pointable/instinctive for quick shots, a heavier or longer or heavier barreled gun can be more continuous in a swing due to its inertia.
I have a Beretta 30" fixed choke that is a nice gun to shoot it's ballance feels very good to me well. Ballanced on the hi he pin without excess weight. I also have a 30" multichoked Benelli Rafaello Super Sport with Briley weighted mag cap, its chunk longer than my K80 Super Sport was but lighter to swing and use, still steady but much easier on my lower back to stop it's movement and get on a second clay.
So barrel and gun length alone isn't the only factor to my way of thinking. It's about how much weight your holding in front of you,where that weight is ballanced and it's inertia.