Bill and I shoot with what I suspect is a representative flyer club here in N. VA. On a given Saturday, Ken's observations would be proved about right. One of our better shooters uses a Fabbri built as a pigeon gun. In hand, one has a sense of a late night liaison between a clays gun and a light trap gun. A "club" is most assuredly not a word that comes to mind. Several of our members use 21s. They range from Heavy Ducks to trap guns to a wonderful high grade dual trigger M/F field gun. I'll leave the argument about the handling qualities of the big Winchesters for another day and topic, but the old field grade gun is a lively thing. One of our better shots uses a wonderful old Purdey, damascus hammer gun with original heavy proofs. Tight and tighter drops them in the ring with authority and again, even an uninformed critic would not tend to think of it as a club. At those shoots over the last several years I have used a Greener Empire (32/F/F), AYA OU Mod 37 (30/IM/F), Beretta BL4 (30/M/F), Charles Daly Lindner (30 Dam/IM/XF) and probably a couple of others. My latest project is an Elsie Specialty set up as a trap gun (30/F/F), and I'll test drive her on a shoot before the end of the year. I have been in the money with all but the Lindner at one time or the other.
So, within their general range of use, "pigeon" guns can vary a lot depending upon trends (and remember a group like the above represents, in their gun selections, more than a century of trends), individual tastes, and what the shooter can afford. None of the above guns (with the possible exception of the BL4) is proofed or designed like a field gun, so comparing them with that genre is largely a waste of time. All would largely conform to Ken's list of attributes.
Comparing them to 1 1/8 ounce proofed game guns makes as much sense as bringing my 7.5 lb Lindner on a quail hunt, or my 6.5 lb Osborne into the Pigeon ring. Within the sphere of their intended use, the nuances of their differences are as intriguing to their users as are the ideas one sees in play on a clays course or skeet field. And it is a great sport.