Hello 
We’ve already been around for nearly 10 years so the long term prospects are looking good.
XF already powers some of the biggest forums on the internet:
[URL unfurl="true"]https://xenforo.com/community/threads/the-large-xenforo-forums-list.87974/post-861167[/URL]
Two of the lead vBulletin developers left vB to create this software.
As for your other questions, I can’t really answer that fairly, but I can tell you that we tend to see more people coming to us from vBulletin than choosing to stay with vBulletin 5 and although there are other solutions, we like this one 
Jokes aside, we’d recommend trying our online demo and that of some other alternatives and then make a decision based on that.
But certainly if you have any specific questions about the software, we’re happy to help.
