Thanks for all your help.
I did contact EditShare and, as most of you have said, FCP X is not qualified for use with EditShare. They are still in early stages of testing it and say it seems that media sharing from the EditShare works ok, but project sharing may be an issue. They say that ‘software updates to FCP X itself may add, remove, or alter how the current 1.0 version behaves’.
FCP 7 it is for now then : )