Not that it would be of much assistance to you, I am considering a switch to MP, after spending about four years with SK EuroBonus, after their recent vicious, sudden and mean chop to non-flexible fare mileage accrual rate. This practically brought them in line with M&M, which is good only if you fly EXCLUSIVELY flexible economy and above. I know few people who do that.

In my approximation, MP is currently the best for anyone who does a few flights a year in restricted economy.

I am aware of the risk in case UA goes under, but I have reasons to believe MP obligations will not be written off by whoever takes over the business. No-one in their sane mind can afford to slap the best customers on their face like that. Relative to other costs, loyalty miles commitment is not that expensive and it can make or break customer goodwill in a major way.