I have already hacked and themed my site perfectly in vB 3.0.1, and wasn't planning on upgrading, but when there was a flaw in the WYSIWYG poster (wow, how convenient, one of the greatest features of vB), I was stumped.

Should I upgrade and spend all that time rehacking (like 10 hacks, some major) or should I just not bother?

There are some optimizations in the code. i noticed minor differences with the update. its always good to stay on top of upgrades

Yes I think it's good to stay on top of upgrades !

You haven't to reinstall your style !

You only have to modify your php file !

Personnally I write an install file for all my modifications ;)

Yeah, it's worth it. I usually put it off, and sometimes I am a couple releases behind. But it laziness. Cause as soon as I actually step forward and make the upgrade, it's very easy.

Also, being prepared really does help.

Not only for bug fixes, but also for security : Yes, it is worth the upgrade.

All vBulletin upgrades have a purpose, otherwise they wouldn't even release a whole new version if it were pointless. So I suggest, upgrade. :)

If I upgrade, I have to rehack my vBulletin again, correct?