Premier members aren't subject to the mileage cap, i.e. fly 25k or 30 segments in 1 year.
I have a UA card but am seriously thinking about getting rid of it, primarily due to the annual fee. I now rely heavily on Hilton HHonors affinity cards with no annual fee. Note also that you can indirectly earn MP miles with the Amtrak fee free card.
I too think the MP dining is a great deal, and an easy way to rack up points - which is also why I am wondering how much longer it's going to last?