Eoin,
I have never read from a limit with regard to data amount. I think, you
should try to increase the timeout of the webserver
(Tools-Options-WebServer Configuration).
Possibly that eliminates your problem...
The following document lists all limitations of remote panels:
http://digital.ni.com/public.nsf/allkb/21B9A9C913F54F918625703D004D6FD9
Regards,
ThSa