We have UBB 6.7.3 and it works extremely well for our customers. We have no intention of upgrading.
However, we need a few modifications made to this, and are willing to pay for these changes. I can outline them for you and you can give me a price to do it.
If you are skilled in PHP and understand how the code works in UBB 6.7.3, and can make modifications - our needs are immediate.
contact me at firstname.lastname@example.org and put "UBB" in the subject line.