Heh, Morgaine, I enjoy the dialogue too. And I hear you about IPB, believe me, I don't really want to go with it over Xentoro. The main reason has nothing to do with feature-set or performance, but because of my user base, who are mainly older and like things simple. I'm currently using SMF for my forum and have been for most of the time I've been running it, since 2005. I switched briefly to IPB a couple years back and got a lot of grumbling for it. Actually, it was about half and half, some people were adjusting to it fine. But in the end it was my fellow admin who was a big deciding factor, she was doing a lot of the work and I switched back to SMF largely to keep her happy. But also IPB was missing some basic administrative features that I had gotten used to with SMF and wasn't thrilled with doing without, such as being able to mass move topics at once. But now my other admin is gone and I'm doing most of the work, so I can be a little more selfish now, and IPB has matured some, and 4.0 is on the horizon and looking very tempting. But still, after doing a lot of comparison between the two, Xentoro and IPB, I think most of my forum will be happier with the former's ease of use, and so that's what the main deciding factor was for me. At least that was the case until I stumbled on this issue. This is one of those big things that could absolutely make the users experience NOT as simple as what they're used to, so... Well, no sense belaboring the point, I'm sure you get it.
And in fairness to IPB, one can argue that the whole question of which software, IPB or Xenforo, has the most dependable addon community is a bit of a moot point when you consider that IPB has a lot more core features - so you don't NEED as many addons. And I hear a lot about how much faster Xenforo is, but I'm not convinced of how much more better it would perform if you tagged on all the addons you'd need to give it even just two-third's of IPB's core features. Even the way Xentoro displays subforums likely gives it a performance edge, as I noted above, but that too comes at a cost for some of us. I'd rather have the option of taking the performance hit in trade for the convenience.
And finally, yes, I might be in a minority when it comes to the number of subforums I have, but guess what? SMF, a free platform, was displaying them just the way I wanted and performing just fine - and it was doing that eight years ago. The main reason I want to switch from SMF is simply because, even with the best of themes, it just looks and feels old to me now and I want a change. Hell, we all need a bit of change now and then, right? But I tell you, so far as features and ease of use go, I continue to be surprised by how the paid solutions fail to stack up against it in some ways.