Interesting promotion, with minimum transfer being 1/4 million MR points, not sure how many people will actually take advantage of it. If I had 349k MR points, I'm not sure I'd convert them to Skymiles for Silver Medallion status and only 10% bonus.
Except for the Medallion status, the bonus is actually pretty lame. I remember a bonus I took advantage of a few years ago, transfer 20k MR points and get 5k bonus Skymiles (20k->25k), for a 25% bonus. Doing the top transfer here (500k, 20x more than my transfer) only gets you a 20% bonus.
Jeff