I don't think it's the MF:SR wait times alone. It's the low wait times at other rides both in DHS and DLR. There was a huge concern that DHS could not absorb the crowds like DL could. So far, the opposite has been true. Lines for Slinky, ToT, and TSMM have been lower than ever, including opening day. We'll see what it's like this week after the hurricane cancellations. But I feel like that should be over with by now and Slinky is sitting at 40 minutes during the busiest time of the day.
Whether it is a "success" or not, I don't know. But I do LOVE what it has done to Studios. Other than having to book dummy 2nd tier FP and tap in for them, everything about this park just seems better now. The 6am EMH are one of the greatest free perks in years.
I also love the decision not to use FP for SR. If FP makes a ride have 3 hour waits, and the FP is next to impossible to get, then it should just be done away with. Of course the other side of it is rides that never needed it to begin with creating standby waits like Pirates, HM, Small World, ect. If you start taking out all these rides from the FP pool, then there aren't enough for people to pick from. A real double edged sword.