Hello Hickmana,
I work in support and have seen a few companies use it, the tool I remember (it was stamped on the converted documents) Transend Migrator - this is not an endorsement or recommendation. I was not involved in the conversion process so can't help on this front.
The customer then had MSG files which could then be processed within Clearwell, the performance was the same as other MSG files.
Hope this points you in the right direction if nothing else.
