We are planning on upgrading our forums in the next few months. After an evaluation process this summer, we have decided on using the latest version of InstantForums as a replacement for this version. We are on v2.9, written in VB.NET and the latest is v2016, though they've released almost every year since 2010. We last licensed this in 2004.
A test upgrade to the newest version of InstantForums went well this week. As of this time, I am not sure of the time to implement, as we have some changes to profiles and integration that they don't have. We are licensing the source code again, and getting the DAL code, which our developers will rewrite slightly to allow integration in a few places.
Outside estimate is 2-3 months, but after a 2 week sprint, we'll know more.
If you have questions or concerns, or there are things you feel are important, please feel free to respond.