The BenQ model you mentioned includes a "flickering backlight" feature which gets rid of motion blur and gives you CRT-like motion. This feature is great for stuff like strategy games, scrolling, or any type of motion where you are trying to track a moving object.
To see the effect this will have, see this link:
http://www.blurbusters.com/faq/60vs120vslb/
Image 1 shows how ALL 60Hz LCD monitors will blur motion (TN or IPS, it doesn't matter)
Image 2 shows how 120Hz helps reduce blur, but it's still pretty blurry.
Image 3 shows how the special backlight strobing feature gives you very sharp motion close to CRT monitors.
As of right now, there are NO IPS monitors with this feature that gives you CRT-like motion.
All of them are TN panels, except one ... Eizo Foris FG2421
http://www.blurbusters.com/faq/120hz-monitors/
The Eizo has an MVA panel, which is kind of a middle ground between TN and IPS. MVA can have excellent black levels (and a great picture), but suffers from slight color changes in the corner of the screen (where the viewing angle is not perfectly 90 degrees). This really only matters for stuff like image editing or other tasks where you create something on a computer. However, it offers a nice alternative to TN panels.
Note: a second bad thing about MVA is they often have a few dark shades that have bad response times.
August Edit: Sometimes the response times of these few shades can have a noticeably bad effect; sometimes it's not so bad. There were a number of things I liked about my old MVA monitor (and some things I didn't like as much). However, looking at reviews on new MVA models, it seems you also have to watch out for quality control problems with the picture quality and overdrive. This newer Eizo seems to have some of these problems, so take care before you consider an MVA or this Eizo in particular.End August Edit
Here's a review on the Eizo:
http://www.tftcentral.co.uk/reviews/eizo_fg2421.htm