Hey - I'm one of the founders, maybe I can comment on this. You're completely right, first sale doctrine is something that would be applicable in a case like this (at least to my knowledge), but a users rights can be restricted by the EULA (End-user license agreement) and Terms of Use and Conditions when purchasing from a store.
The actual adaptor we planned to use didn't have any EULA restrictions that would have prevented us from going forward, however we at the last minute found out that the places we were purchasing these from did have Terms of Use restrictions that weren't favourable to us.
Though our situation was more of a grey area than a black and white one, we decided that the cons outweighed the pros. After all, our legal budget is a little lower than that of Apple :)
The actual adaptor we planned to use didn't have any EULA restrictions that would have prevented us from going forward, however we at the last minute found out that the places we were purchasing these from did have Terms of Use restrictions that weren't favourable to us.
Though our situation was more of a grey area than a black and white one, we decided that the cons outweighed the pros. After all, our legal budget is a little lower than that of Apple :)