I have the original Jelly head choke tube in .660 & .665. The patterns are pretty much the same out of my 870 Special Purpose Mag. I also have the H.S. Undertaker(.665), but don't remember how it patterned. Right now I'm using a Carlson .670 non-ported tube(about $35) & shooting Longbeard 5's. They were way to tight for me at 15 yards with either of the Jelly head chokes....pattern is about the size of a baseball. Using the .670 it is about the size of a cantaloupe. The 40 yard pattern is still a very solid hunting pattern. I have not tried the new Jelly Head Max tube. It is designed a little different than the originals. Here is a post from Clark...allaboutshooting here on OG, from about a year ago:
"The major difference is in the "internal geometry" of the choke tube. It is still a conical/parallel design but hey lengthened both the taper and the parallel sections. The ports are a bit longer and thinner and they eliminated the knurling at the muzzle. They coated it with a very tough material to prevent rust. All in all it's a more finely made choke than the original
I suspect that the "Black T" coating requires more break-in time than the original blued choke and that may account for folks not having the results they expected.
I hope that helps some.
Thanks,
Clark"
Here is thread from a few weeks ago about the new Jelly Head Max:
http://oldgobbler.com/Forum/index.php/topic,96562.msg949182.html#msg949182