Samsung and IPS? My first thought was:never! But on some Samsung sites the 170T is featured to have a TN/CE panel .This refers to the electode configuration but is typical for IPS. Samsung itself never mentions IPS on any of its monitor or LCD-panel sites (at least I haven't found one so far).
I checked a patent database and found two patents about IPS filed by Samsung. So they have this technology but may be they just use Hitachi panels for some of their monitors.
All Hitachis 17" panels (IPS) are slower (35ms and 30ms), you can check them out here:http://www.hitachi.co.jp/Div/mobara/catalog/tft-e.html#super-ips
Samsung has some "CE" panels listet but they are slow as well.
Anyway, it never has a **total** response of 20ms.
Samsung monitor data sheets are really messy. You always have to cross check various country sites.