Personally I would take the XD over the Glock any day of the week (my current carry gun is a XD-45 Tactical)
But straight value to value the Glock package is worth far more than the XD. If you could get him to go for it then do it, IMO. I would bet the 9mm conversion kit alone is worth as much as your XD. Throw in the threaded, extended barrel with "training supressor" and it's really a no-brainer.
I think there is likely something wrong with the gun or something wrong with him... but it would be a sweet trade otherwise.