Upgrade or not?
 

I am running version 3.8.3 and was thinking about upgrading. The problem is that I have hundreds of custom pages that I have added and was wondering if these would still be functional on newer version. I'd hate to have to go through all the work of redoing these again. Any thoughts appreciated.

Are you talking about an upgrade to vBulletin 4? If so, it's very likely that most plugins and custom scripts will break.

You should upgrade to version 3.8.9 at minimum for security reasons.

I would recommend making a test site for version 4.2.3 so you can see the actual changes before you make a permanent decision on which version to use.

vB5.x is another discussion entirely.

I agree with ProSportsForums, upgrading to 3.8.9 is the way to go for the sake of security reasons. Upgrading major versions just for the sake of upgrading is unnecessary unless you are taking advantage of features not available in your current version.

Upgrade to vb4x will brake all plugins and addons so I will go with ideas of Replicant. If the difference between 3.8.3 and 3.8.9 is about security then it should be done immediately.