Re:From a practicality point of view, a single set of forums for all the products is better.
This is the wrong way to approach it. You are seeking for your own confort rather than from your customers. How many of your customers will have two products from you? My guess is very few... most will have either system. I understand it is much more practical and less work for you to just have one system for support... but that is wrong, why should any customer care if the support forums are different? They will most probably (98% of the ties at least) only be looking into the support forum of their program. For example, I will probably never need to get into the Open Topic boards... but if I do, I would expect them to be on Open Topic, and UBBThreads on UBBThreads...
Think about what your users and customers need, not what is easiest for you!
+you should be interested in using it as well! As I said in an earlier post, that helps finding bugs, enhancements, ideas, etc...
