Trust...eBay....Mmmm, I know a few PC's off eBay that do odd things! You pays your money and takes your chances... :S
Had a couple this year that were S hand, they were mapped OK but did some odd things...without going into detail the owners now run with no PC at all and say it 100% better! PC's are just a means of correcting the bikes AFR I like Dynojets products but anything electronic can have its problems... I run PC's as I like my motors AFR to be spot on.. I'd buy new and think of the extra money as insurance.. unless I knew the score..
Some have come off crashed bikes which shocks the electronics the same applies to alarms and have come across several that have been involved in a big offs. Once disconnected the bike ran as normal these units are very fragile. BEWARE