AFAIK Reaper itself doesn't support multitouch beside some gestures, so you e.g. can't adjust the volume of to channels in the mixer at the same time. Multitouch support for plugins depends on the plugin itself, some allow to move simultaneous (i think, those with are built upon newer versions of the JUCE library
http://www.juce.com/about-juce), e.g. The Mangle. But they are the exception, I think with NI products you are out of luck.
When I bougth a Transformer T100 some month ago, I planned to use Usine, which is one of the few hosts on Win, that have multitouch support (I think Sonar is the only alternative). But after some testing I decided, that usability is more important than multitouch and moved back to Reaper.
I really hope that the situation will improve in the future.