No major updates in recent times, Kier never seems to be online, there are a lot of worried people regarding the future of XF.. Quality hard working staff leaving etc etc..
On those points...
1) 1.1.3 was released 2 months ago. That is the most recent release. 1.2 has been delayed. The popular feature in 1.2 is the mobile style. If mobile support is important to you then you may wish to wait. Or there is a third party mobile style you can use:
http://xenforo.com/community/resources/xfs-mobile-style.290/
Tapatalk is also a popular mobile app that supports XF:
http://tapatalk.com/
Tapatalk's support forum actually runs XF.
2) I see Kier online regularly. Though he might be invisible. As a moderator I can see invisible people so I'm not sure.
3) See this thread for worried people:
http://xenforo.com/community/threads/the-concern-thread.34838/
Unfortunately I had to lock it because it was getting out of hand. People attacking each other and stuff.
XenForo has been fighting a lawsuit for nearly 2 years which has eaten up all the money. That has consequences. If that worries you then you may wish to delay your purchase. But I think most people recognize that the lawsuit is frivolous and it's just a matter of time until XF wins. The trial date is currently set for January 15, 2013. Personally I am not worried.
4) As for people leaving, you must be talking about Brogan since he is the only one. He left for two reasons that I am aware of:
a) he wasn't getting any help with moderation and support.
b) he felt KAM should be more transparent about the business / software.
Well I have since taken on his mantle as the most active moderator, and I'm not going anywhere. Though many people agree with Brogan that KAM should be more transparent. The lawsuit means there has been no money for 3 years. That has consequences.
I would like to use XF for about 3-4 upcoming projects
What projects? Let me know if you have any specific requirements. I can help you put everything together.