TN screens tend to be faster at a cost of color accuracy and viewing angles(view from the side/above/below).
IPS panels are FAR better for color and viewing angles at a cost of overall speed.
60 to 120 is noticeable to most gamers for sure(even without 3D). I personally have mid way point(S-PVA) screen with rather good color(better IMO than many i see today) and mid level response(for a screen that is 5 years old). Next to a TN it looks better but has more input lag for sure(some users will not notice it while others may go nuts).
I always recommend looking at the screens in store to see what YOU like since specs only go so far.
Another thing you may wish to look for is IPS glow as some users do not get bugged by it, but it drives me nuts.
This IPS screen at MAX brightness(dynamic contrast was OFF) was not only darker(It had a "game mode" that fixed the darkness but made everything all banded.) than my other screen at 23%, but had some bad glow. Again, many users do not notice or are nto bugged by this.
This does NOT mean IPS is bad(quality screens with a polarizer have NO glow.). I have seen some good cheap IPS screens with way less glow from LG.