Doesn't always work. I had a 2-year engagement so got an apartment and lost all status. The following year Marriott gave me a plat challenge (18 nights to plat(?)) based on my previous expereience with SPG (plat for 3 years). I had an opportunity to switch back to SPG and was going to, but they refused to match status since I'd already been plat in the past... so they've lost ~$25k from me in the past year. Why would I want to re-earn plat with SPG when I'm already receiving the perks & benefits as a Marriott Plat, and have a choice of SPG or Marriott properties?

Sometimes the status match won't work....