Yes you can switch lenses if you have an assistant(PA budget is the best spent money on set) and yes there are times when you can take advantage of the RS, but mostly it's a very annoying workaround. Funny how most of the responses on here have been how to technically avoid RS, but none have offered an answer to shooting with it.
I get it. Some folks really need DR(although most are just shooting crap for vimeo). DR isn't king though. To me the images out of 99% of the footage that I've seen from the a7s are pretty flat, lack color depth and don't really excite me. The one small clip that I've seen of the 10 bit footage from the GH4 blows away even the the Den Lennie footage in 4k that is graded. Call me crazy, but again I've seen enough. To me the with a 10 bit(doesn't have to be 4k)recorder the gh4 is a poor mans RED. The a7s footage looks just like a beefed up 5d with more DR(even on Den's footage).
I have a 5D fully hacked RAW and while it's good it's DR isn't as good as you think(the 14bit footage is amazing to grade though). You have to consider the fact that you're using a hacked camera, which has totally overheated on me shooting only 35mins of RAW at a concert. The bottom line is that it is still a hacked camera and really not one that should be used on hired gig. Have you even used a 5D hacked? You can't review footage in real time, it doesn't always record the clip(95%rate, but still not good enough), and it's fucking nightmare in post to work with. I've run ML many times on shoots, but due to the fickle nature of RAW, I end up shooting h.264 most of the time to be safe.
So yeah. I'm gladly switching to a GH4 that has an unlimited record time, 10 bit output and I really like the subtle softness of the m 4/3 look. Biased? Maybe, but consider that I was a dedicated Canon shooter(C100 and mkIII) until a few months ago... Full frame and DR aren't the end all be all.