UBB.threads PHP Forum Software Community Forums UBB.classic UBB.classic 6 Support Upgrading to 6.7.xxx ???

I'm inheriting a website using UBBClassic 6.4.0.

I'm trying to learn all that I can about the forum software, although it seems that so far everything is running just fine. (The thing is running itself!)

So, the question is to upgrade to 6.7 or not. If it ain't broke don't fix it?

Your opinions, if you please....

TIA