As a former moderator of a large forum with over 10,000 users—which had to be migrated twice over the years—I understand very well the challenges you’re facing now, and I’m genuinely glad you’re taking this step nevertheless. XenForo is an excellent choice and will undoubtedly enhance the overall experience. Several other forums I regularly visit use it as well, so I’ll feel right at home.
I especially welcome the feature that hides large quotes, since this has been a persistent issue on the current forum. And I certainly won’t miss the threaded view—it felt outdated twenty years ago already, at least in my opinion.