Personally, I sort of like the numbering starting at a number other than 1, as James says you most likely will renumber most things anyway, this includes parcels. In this case one should set all numbering sequences high (10,000) and then renumber as required with little chance of overlapping.
It would be interesting however IF no number could be assigned during the layout phase, and then begin numbering these items as they were added to say Groups? In this fashion the user could extend this to using lots, and blocks within a parcel numbering scheme, segment numbering, or even Phasing. The user could define a group, and have the position within the group determine it's numbering schema, and let it be repositionable within the list.......