I am about 35% to lifetime gold on nights, over half way there on points, so I would like to say I'm in a similar position.

That being said, I just made the move to SPG and I have to say I'm much happier than with MR. I will continue to stay at MR when SPG isn't available or when I reach PLT on SPG and need to level up on MR. In the end, the decision is yours, but with free internet on SPG, more resort locations I'm interested in, and IMO better customer service, I think I made the right decision.