Just wanted to let you know I purchased an Asus VG248QE 24” 144Hz screen the other day and this monitor has a TN panel.
There is absolutely nothing wrong with using a TN panel - I find all the talk about offangle viewing being screwed severely blown out of proportion.
Either that, or there is a difference between different TN panels.
This monitor I'm looking at right now, I can tell you there are no problems whatsoever unless you're looking at it from an extreme left or right view. If you do that, sure, colors change a bit, but that's it. You can easily sit two people in front of the screen and watch it without running into this offangle viewing problem.
Edit:
The other person sitting in front of the screen will actually experience a difference in color in the far left side of the screen.
I just tested to be sure what I was saying was correct.
But using this screen just me, I'm never running into problems with the TN panel.
Out of the box the monitor was very, very bright, but once calibrated with the correct ICC profile, everything looks great.
Colors are a definite improvement on my 6½ year old Samsung 19" 930BF screen.
You can find ICC profiles for various monitors here btw.:
http://www.tftcentral.co.uk/articles/icc_profiles.htm
If I were you I would not hesitate to get an Asus monitor with a TN panel.
But you might want to wait for that Asus ROG 27" screen that is in the shops in 2 months time or so.
It has a 1 ms. response time and is 120 or 144Hz (can't remember which)
Good luck with your purchase.