Plantronics + Polycom.
Now together as
Also Susceesfully field tested, Group SeriesTouch Display Interface Control
IIyama – PL4664 Multi touch
IIyama – pl5564 Multi touch
Polycom internally uses Dell touch displays and has had success with them. It is felt the technology they use in their touch is the best and most responsive.
How to test the responsiveness of a display.