Hi Johnny, congratulations on the car and welcome to our forum!
I don't think Renaults are any different from other cars in this respect. You probably have a leak in your cooling system, which is probably the water pump as you suspect. No, I don't think it's a common fault on the V6 - no more than on all other engines. Pump bearings do wear out, and then they leak and cant keep pressure up. The lack of pressure is usually what's causing the boiling and overheating.
The water pumps on the Espace J63's are relatively easy to do since they are fitted on the front of the engine. Remove the radiator and you have easy access.
I hope this helps. Good luck.
/Anders
PS: I see you're in Denmark. Do you know my list of spares supliers (scroll down):
http://dinsen.net/espace/reservedele