We have never traveled RSVP, so I can't compare. We have always gone mainstream, and have never had an ounce of trouble, ever. It may not be quite as rambunctious and lively as RSVP, but it is sort of nice not to be bombarded 24 hours a day, and to have some solitude. There are usually meetings on board these mainstream ships called "Friends of Dorothy" or FOD for short. You get to meet with other gay people onboard your ship.
I will let you know how this inaugural cruise goes. We are very excited about the itinerary!