re: does anyone here know someone who got an MLOG degree?

Well the average at Stanford is a 728. A 730 GMAT is 96th percentile. About 250,000 take the test each year. So 10,000 score above a 730, but there are only 4,400 spots in elite b-schools. It takes a lot more than a test score.

I may be way off, but I think most motivated, successful people covet a managerial role at some point in their career. That move will be much easier with an MBA. The quant guy usually remains the quant guy. Granted, that is sometimes by choice. All that said, if you need to make this call at the age of 22, I'd definitely favor the broad degree over the niche degree.