The difference is huge. To quote myself
frknI noticed a huge difference using lightboost on my Asus VG248QE.
I sometimes get this bug where i move in slow motion in source games (it is related to C++ somehow http://forums.steampowered.com/forums/archive/index.php/t-635372.html )
When I went from 120Hz->120Hz lightboost, I thought I had that bug. Everything was so crystal clear, I thought I was moving much slower, but I wasn't. It was definitely noticeable. That being said, I didn't think it provided much of a benefit compared to 120Hz non lightboost. While there was less motion blur and tracking was a little easier, there was a slight increase in input lag. I think these 2 effects effectively cancelled out as far as tf2 goes. I think it may be more beneficial in games where enemies are camoflagued, etc. I concluded that I definitely preferred 144Hz, while 120Hz lightboost and non-lightboost were a tossup in tf2.
But this was just plugging my monitor into my friends desktop, now I'm back on my laptop stuck at 60Hz :(
frknThis is true, there is definitely a lot less motion blur. The thing is, I don't have any problems with the amount of motion blur present at 144Hz, it doesn't affect my tracking at all. The amount of input lag increase, while small, is noticeable enough to affect gameplay. Although I was able to adjust to it, in a game like tf2, I found the decrease in motion blur didn't really outweigh the increase in input lag. I think it would be more beneficial in games where enemies are harder to spot (camouflage, etc) than in tf2 where enemies stand out quite a bit.
Plus the colors are better without lightboost (even when using a lightboost calibrated ICC profile).
I have been able to notice more ghosting on 144Hz, which was nearly impossible to see after the 60Hz->144Hz transition. I would like more time to play around with it, as I only used lightboost for an hour or so in dm/mge/pubs. I am starting to feel like that clarity actually did help but can't do extensive testing until I build a desktop.