I purchased 34UM95 in Frys for 999$ + tax. Display looks very nice with some limitations. Backlight bleed is noticeable in the left bottom part. In other forums was mentioned that this is widespread issue with this display. I returned the unit and hope to get Rev. 2 later.
On the positive side:
Display worked without issues at full resolution with rMBP mid 2013 and rMBP late 2013 via Thunderbolt.
Out of curiosity I plugged the display in white MacBook Core2Duo http://support.apple.com/kb/SP584 . This machine do not have Thunderbolt, only mini display port. When connected with mini display port to display port cable display worked without issues at full resolution with 60Hz. It was quite surprising as this machine is ancient.
You should make sure you aren't experiencing IPS glow. It seems many are confusing the glow with backlight bleeding. At these widths, the glow can be seen when looking head on.