In theory, a longer transition to the smaller diameter will give more time for the pellets to relocate and deform less which in turn should reduce flyer pellets and produce better patterns. Some manufacturers build in a parallel section maybe 1/2 to 3/4 inches long at the muzzle end which allows the shot column to stabilize at the smaller diameter before exiting.
Does all of this extended choke tube technology produce better patterns than flush chokes? Maybe and maybe not, I think a lot depends on the ammo used. Obviously lead shot with higher antimony content will deform less than lead shot with less antimony and long forcing cones contribute greatly to less pellet deformation, possibly more so than the choke tube itself. On older guns the forcing cones can be 1/2 to 3/4 inches long but newer guns can be 4 inches or in some cases such as the Dt11 much longer than that. I’m a big believer in long forcing cones, maybe not the entire length of the barrel per say but certainly several inches.
There’s been innovations in choke tubes that are note worthy and Muller Featherweight’s fall into that category. They are made of aluminum with a ceramic coating and in my experience produce some of the most consistently dense patterns that I’ve seen. They’re much slower than some other tubes to build up wad plastic in the throat area.
Briley and Teague are also some of the best tubes I’ve used.
Extended tubes are handy for those sporting clays shooters who change tubes often but ported choke tubes don’t do anything except make noise and annoy your shooting buddies.