Remote Buddy does not do anything strange with iTunes nor XHub, 
though. It uses iTunes trough AppleScript (like everybody else) and 
currenly doesn't have support for XHub and thus also no routines 
specific to it. So I don't see how it could affect what XHub is doing 
or how it is performing.

Thus, please file a bugreport with the author of XHub, so he can look 
into and ultimately fix the problem. I'm not the right addressee for 
XHub related problems.

You can, btw, use the Virtual Remote of Remote Buddy to 1:1 emulate 
Apple Remote button press events (regardless of whether you have a 
built-in receiver or which remote you use), so you may want to try 
that approach, too, should the use of keypresses not be properly 
handled by XHub.

Best regards, 
Felix