"mao, how much work does it require to do a fit? In hours I mean. Say fitting a fairly standard dress from V3 to V2 or from V2 to PT or some such."

Once you get the hang of the program, conversions usually range from a few minutes to an hour or two. From my experience, V3 to V2 conversions are fairly quick and simple, but conversions such as V2 to PT need alot of reshaping to fit right, and can range from 15 minutes to an hour, depending on the type of clothing being converted and how well you want it to fit the target figure.