I never experienced the transition from YaBB to YaBB/SMF that much because I only came to the community forum when there were serious problems. Sometimes it took a few days, but usually I was helped within 2 days. Maybe that's the reason we didn't look further, because if the the support forum wasn't friendly to me I would have already made a switch at the time. But Spike helped me a lot and Jet Lee and with them I never had any problems.
It was the choice of my ex colleague admin, to take YaBB and NOW there is no talking to him about it without getting annoyed, even when I ask him why he quit after only a year.
But if I had known all this in early 2005, I would have already made a switch, after all, back then the forum was small, and the risk of crashing idem ditto.
Maybe there should still be a YaBB26 converter.
But I don't know what kind of forums you have, that of @ pyragony54 I know, but my forum is a forum, with a lot of translated news about for example the war in Ukraine, about the worthless politics in Poland and their neighboring countries. For that reason, I think it would work for me if I started SMF and made the Current Yabbforum static as an archive.
Old news is only important if you need it as study material, that's what it's used for a lot so additions to it are not needed.
"If it ain't Broke, Don't Fix It" . . . . . . Know it, we use that here too.
But why do extra work, to install phpBB in addition to SMF? I'm often already working 13 hours a day now and continuing on a new SMF, that will add a month of extra work, but after that there is peace again. Remember, I do everything for free there is no one who pays for my work, because at the time I made the choice to do something on the Internet, so that the gray matter in the upper chamber does not fall silent after retirement. But I MUST continue to think, because when I close my eyes, others must be able to continue.
Most users of my forum would rather be lazy than tired.