FOUND ONE.
Shnikies as Chris Farley would say. For the past hour since posting that I've been looking in google. I'd rather have dental work!!! So much junk comes up in google anymore. Totally useless, waste of time sites like "shopwiki".
Anyhow, I've ordered this. I'll report here if it seems high quality, in case anyone else finds themselves in the "bind" no pun intended. I don't know what the professional pole pruner companies are thinking not to make such an adapter to use their blades, but, oh well.

Here is a link that might be useful: http://utrimit.com/screwonsawhead.html

Thanks for posting this. I've looked for something similar and ended up hiring a professional tree trimmer.

The pruner that I was looking for was the type with a rope which that site also sells.

I think you are right to be concerned about the flex in the pole. The guy I hired had a pole that seemed very rigid and they had no problem controlling the end 25-30' away.

Let us know how it goes!

Here is a link that might be useful: http://utrimit.com/pruningheadlopper.html

OK...there's a reason few people sell such an adapter. The flexing a major problem. If you want to do this, just shell out for one of the dedicated poles. That being said, it was worth it in a strange way.

I had a 3 way forked hemlock branch. Underneath was a minefield of rare broadleaf evergreens and woodland plants; I'm not sure I could have trusted my regular tree service guy not to hit one even if he was using his bucket. His crew can be a little careless. It would have been impossible to start with a relatively more common rope chain saw because of this arrangement. The chain would just slide into the crotch and get stuck. By using the part I bought, I was able to get the center branch out, but it was incredibly arduous. I mean, we're talking over 3 hours of struggling with the thing. The pole just wasn't up to task, and the last extension segment kept pulling out of its socket. But I finally got the center one out. Then, when trying to use the saw on the next branch, from a different angle, the middle extension completely bent on the end. No matter, it was aluminum so I just cut it off with an angle grinder and the MrLongArm pole is now about 7" shorter! But I decided I had to switch to my old rusty rope chain (the one sold by Northern Tool IIRC) and I got the other 2 down.

What they send you is still a very usable hand saw; and I'll probably use it on a pole in the future for much shorter 8-12' extensions. If most of the aluminum is tucked into the fiberglass, the LongArm pole is reasonably rigid enough.