The gConverter team helped me migrate a very old UBB (wwwthreads) database into a new XenForo installation. There were very few conversion issues on the first pass, and they cleaned them up quickly, exactly according to my request.

I was concerned that this was going to be a difficult migration but gConverter did a great job at a reasonable price. I definitely recommend them and would not hesitate to work with them again if the need arises.