I have been playing one of these since December 1988. I have received nice compliments on the sound. What have been your experiences with it?

I had one in the late 80s, when I was in my 20s. I used it in a pretty good amateur orchestra. It was great for loud stuff, but it required strong chops to drive it. I got rid of it when I left the orchestra. It wasn't as good as my 88h for smaller groups, but I loved playing it where I could cut loose. More Bach than Conn, but noticeably a combination of characteristics.

I feel bad writing the same thing for the millionth time on here, but I have never played another trombone that allows me to get my idea of the perfect principal trombone sound with absolutely zero effort. Pick it up, play it, instant principal. (And I do not play principal very often!) I've played both 156/256 and 158/258 examples that have this magic, but I recently played one that did not so it's not universal. If I played principal trombone regularly, I would definitely own one and use it for all principal jobs.

I know that some were straight .547" and others were dual bore .547"/.559", which I think came later if I remember right?

Played tuba once with a pretty good community orchestra where the principal was using one of those. She sounded good, and indicated she enjoyed playing it.