I haven't touched BLM or SMN since 4.0 dropped, but I can at least say that RDM is simple to learn, flexible, and quite forgiving. I think it's fun, and probably worth at least trying out a little. The rotation changes some between 50 and 70 obviously, but you can basically learn the entire flow of the job as soon as you unlock it, so you wouldn't have to invest all the time in the world before seeing if you found it interesting at all.