We did exactly that a few years ago. We had 4 days in Paris and on one of the days caught the RER (train) to DLP. Like you, there was just the two of us and we only did the "big" rides. That was perfectly manageable and we had a lovely day. Granted the Studios park wasnt open then, but to be honest, you wont be missing out on a HUGE amount if you miss that park entirely. It would perhaps be possible to duck in to do Rock n Rollercoaster and the Moteurs Stunt show after the parade at the Main Park.
When are you planning on going? We were disappointed with the park hours when we were there (Sept ) and it is much better to visit when the park opens longer. I would also choose to visit on a weekday as the parks are far, far quieter then.
Also, be selective about what you want to do. Realistically, you are not going to be able to do EVERYTHING, so a plan is essential. It does make me wonder why couples without children would stand in line for 45 mins to ride Dumbo, Teacups or the "speedway"!!!!! Fine, if that is your "thing" but if you prefer the "real" rides, then I would stick to trying to fit those in first and whatever else can be slotted in around that.
I would definately DO IT though!! Its a very easy journey from the center of Paris to DLP and we had a lovely day out. It made a change from the city and if you are going for a week, then I would say one day here would be a great addition to your vacation.
Happy planning!