You pays your money and you takes your chances.
I just ordered a GrainMaker after going back and forth between it and the Country Living. Deciding factors for me were the second auger being included, the lifetime warranty on the burrs, and the fact that welded plates are less likely to crack if dropped (relative to the CLM's cast aluminum frame).
I expect they're both excellent mills. There are LOTS of mills in the lower price brackets, but my understanding is that you can expect to grind your grains 2-3 times in order to reach flour consistency, and they'll still be inconsistent. At the top end is the Diamant; I couldn't figure out what made it worth three times as much as a CLM.
GrainMaker is bumping their prices (to north of $600, iirc) this Friday; they were supposed to go up this past Monday but were apparently swamped with enough orders to hold off another week on the price increase.