Hi Big Kids,
You have the math right.
I personally have had no problems with the VEA, its easy to find from my arrivals gate, and I've never had to wait more than 15 minutes for a coach to turn up.
I used RS transports last year when the public transport strike was on in France. It certainly gets you to your hotel quicker, as the driver is there waiting for you at your gate. The car we had was lovely, and the service excellent.
I think its down to personal view whether its worth the extra money or not.
Personally, as you're talking double the price for the private transfer over the VEA, I'd say no, its not worth that much (that 70 euros is what I spend on food for a whole day in the parks).
Elaine