I prefer to play on PVE servers. I do enjoy friendly PVP on PVE server. Past experience has taught me that any class with the ability to take life from the opponent and heal themselves with one spell was very powerful in pvp.
With that said, what if the Blood Mage turned out to be an overpower class that took 2 + players to take out one Blood Mage, how many would find this fun, or challenging. How many would reroll a Blood Mage.
Personally, I found this to be fun and challenging, whether I was the over-powered class or part of the group attempting to take out the overpowered class. On a PVP server, running across an overpowered classes alone can be fun & exciting itself. Yes, the chances are high that you're going to die, but there is always that chance of escape and when you do, be sure to thump your chest with pride
One example I can remember is from playing EQ and being group with 2 friends attempting to take out same lvl bard with more AA’s, better gear, etc. The fight went on forever and the bard ended up killing 2 of us before we could take him down.