Paul,

You really need to speak to the folks at Freedom's Wings International
(FWI). They promote hand controls for gliding in the US and would be
able to put you in touch with dozens of current and former students. I
used to teach for them several years back, and the psychological impact
on folks was certainly impressive. Their website is (was?)
http://www.freedomswings.org (it seems to be down at the moment). You
can also try the SSA, as they ought to have contact information for FWI
..

Erik Mann (P3)