The BenQ XL2420T is not worth the extra cash. Save and put that towards another upgrade.
The BenQ XL2411T is highly recommended. It is the latest model, it also has one of the best LightBoost mode capabilities.
Lightboost mode does require an Nvidia card, although I've now heard AMD cards might be able to.
Lightboost mode further reduces the motion blurr by up-to- 80%~
http://www.blurbusters.com/zero-motion-blur/lightboost/
Check the above out for the facts.
Also the look and feel of the monitor is high build quality, the colours are perfectly fine, although be warned that if you decide to LightBoost enable, it does create a tint, but this only affects when not in a game, games seem to not be affected by this. However it may be different for you.
The BenQ does need the settings changed and a bit of twiddling, but once you have calibrated it to your liking, the monitors performance is outstanding, even without LightBoost.
It's perfectly capable of VESA mount and holds well.
The only thing the BenQ XL2420T does well, is the colours seem less affected when in Lightboost mode. But that is so negligible that it doesn't warrant buying over the XL2411T.
It's the middle one:
http://i40.tinypic.com/2l8775.jpg