I have also glanced towards United and their 100% EB earning on all booking classes.
However, earnings for their own MileagePlus members will change (drastically I think) later this spring and become revenue based.
I wouldn't be surprised if they degrade the percentage earned with EB after that.
After the lowering of points earned on SK metal, there are itineraries to the US where you earn more EB points on UA metal than you do on SK metal - even after factoring in the 25% EBG bonus.
That can't be sustainable in the long run so after both carriers are done deflating their own loyalty programs, they will probably have the time to deflate earning credited to other programs.