Neil Winston over on the trapshooters forum has extensively tested the differences. I suggest you go to that forum to read his results. The site has a search function so that you can find Winston's posts.

I use the Ext. Mueller chokes to shoot Sporting Clays. They are easy to change with your fingers and you do not have to have tube wrench to do it. I also check for them being loose after each station. I use them in my Beretta 12ga. and in my Beretta Sporting 20ga. with 30 inch barrels.
You hardly ever see any one not have Ext. chokes when shooting Sporting Clays.

other than lighting a fresh cigarette, what did the old boys do between shots w/their fixed-choke guns?

Briley

Both types of chokes work very well. Most shooters should probably be more concerned about shotgun pattern, gun lead, smooth swing and follow through.
Extended chokes are merely easier and quicker to change.

There's a lot of good brands, I've had good success with Carlson.

If you own an older Beretta 12 ga. that uses the Mobil chokes and are wanting a pattern Master Black Duck Ported choke tube PM me

I get what you’re insenuating, but realistically one of the most inaccurate things I’ve ever read on the internet...

I would PM Barney Topwater... as one that owns a Patternmaster, and have shot many of birds with it over the years, you WILL NOT be disappointed. Trust me....it’s the internet.

Extended chokes just look cool.....

That too