Kane,
Since I only smoke cobs, chamber diameter means little to me, it is what it is. The Diplomat, Great Dane and Mark Twains also have the larger (3/4s of an inch) chamber. A single Dunhill Flake, folded and stuffed, fits perfectly in my Great Danes, smokes well. A full Sam Gawith bulk flake (5 inches long or so) fits in the General quite nicely.
I leave the filter in for the first smoke or two, some new cobs have a very woodsie flavor at first. After that no filter, great draw, cleaner goes in without a hitch on 99% of my cobs. The older they get the better they are (I have some that have been smoked for 10 years, they get narly).
At the price of a decent 100 g tin...