What happens if don't upgrade??
 

Last week I decided to go with vBulletin to be hosted on GoDaddy. I didn't see all the posts about the Godaddy problems until I had already paid for the hosting through there. To make a long story short* I usually buy whatever seems to be the best with most bells and whistles whether or not I actually need it or not. So I pre-ordered the vBulletin 4* since it was on sale. Upon installation of the beta on my server* I had a lot of issues* I'm not sure if I set up my PHP or SQL on the server at 4 instead of 5* but on a lark I decided to set up the vB 3.8 to see what would happen. 3.8 worked* everything loaded* and the forum is now in use. I tend to follow the path of least resistance* so what happens if I decide that 3.8 works awesome for my purposes and never upgrade to the vB 4 when it's more solid? Will I be subject to major security flaws* missing lot's of super cool new features? Or will I most likely be fine?
I found 3.8 pretty easy to get going* but I'm nervous about upgrading in the future* seems like a lot of room for error if I screw up. Maybe when this hosting plan runs out I'll move over to another server* and everything will work awesome* but I've paid for GoDaddy Linux* and will use it for a year or so.
Dan