Hi Mike,
It is entirely possible to have both v4 and v5 installed on your PC. You would then decide which version you want to run, obviously you can't have both going at the same time. In v5, you have to tell the software what powerbase you are running, other than that you get 30-days of trial running.
As for the benefits ....... well that's why you have the 30-days trial. Having said that I feel that there are many more benefits to be obtained with v5 and if it works on the PB-Pro in the way that you are happy with then I would go for it.
Let us know ho you get on
All the best - Greg