While migration tools are around, you should ask yourself: do I need all this history in my everyday life? When I've migrated source control systems in the past, I usually try to find a clean breaking point (few open branches, etc), and just migrate the head of each project over. I archive the old system in case there are historical questions where we need to see into the distant past, but just moving the head over gives you a nice clean, fast repository to start with. The number of times we've had to refer to the old system could be counted on one hand.
I've never tried the PVCS scripts, but I've had mixed results with others, especially around branch history. Every system is just enough different that the graph is never imported 100% perfectly. Better to leave it in its original form if possible and start fresh!