<soapbox>
Man, the SNR of this thread is freakishly low as regards the OP. People already know LCD's have about a billion advantages over CRT, with a few exceptions. The OP asked about input lag, it would be nice to respond in kind.
</soapbox>
I threw fits when I first switched to LCD, and for nearly two years chose to lug around my trusty old CRT whenever I played a competitive FPS. Now, another eight years later, I had become convinced that my old complaints about input lag were overblown, and that "surely it wasn't as bad as I used to claim."
One week ago I needed to use my old CRT for a short while. As I hooked it up I was grumbling to myself about the weight, and turning my nose up at the small screen size. However, when it actually got into Windows my jaw literally dropped.
Believe who you will, but to my eye the difference between my supposedly "zero input lag" IPS LCD and my trusty old Trinitron CRT is nothing short of a slap in the face of modern LCD's (no hyperbole). Bear in mind that one week ago I would have SWORN that my LCD has no input lag.
Does anybody remember using ps2rate in Windows 95/98 to up the PS/2 polling rate from 40Hz to 100Hz (or higher)? Remember the stark difference it made? The difference between my LCD and my CRT is that noticeable.