I have this setup. I must say I still use my Thunderbolt Display with ease and do not really get irritated because of the a bit less than perfect pixel density. It looks still fine to me (I do see the difference, of course).
But as I (and others, I assume) sit further away from the Thunderbolt Display than I do with the Retina MacBook Pro, I do not really find it an issue.
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Still looks great, just not as sharp!
You have a 17" Antiglare 2011 2.3 i7 rMBP? Seems to me some numbers are being messed up
