This discission highlights the fallacy of a goverment mandated tailwheel endorsement (their fix for failures). I checked out in a tailwheel aircraft before the endorsement was required and was grandfathered as a tailwheel pilot by the FAA. I had no instructor, BTW. That was the late '60's. By government opinion, I should have created an incident or accident by now. Sorry to prove you wrong, bureaucrats.
Pre or post endorsement, one is still (usually) going to get some kind of transition training mandated by whomever owns the aircraft, whether insisted upon by the insurance company or otherwise. I know when I flew the Beaver, I had quite an extensive checkout by the organization who owned them. Would having a tailwheel endorsement (that was never checked, BTW) or not have made a difference in blessing my capabilities to fly that type? I think not. Actually having an endorsement in a specific type to fly taildraggers in general by some governmental body does nothing to really endorse you to be a qualified tailwheel pilot, regardless of type...at least not in my book.
I learned a long time ago that one does not loan his wife, underwear, motorcycle or airplane (particularly a taildragger), and maybe anything with an internal combustion engine, in general, to anyone, including well meaning friends. Its just a bad idea. That's my policy. I do, somewhat hypocritically, accept loans by others if necessary, of some of the above (excluding wives), as I trust myself more than others. So far, the trust is well placed.
Blessings of good karma to all who are in pursuit of good techniques and reputations of dependability...tailwheel or otherwise.