What I was saying before (as SD reiterated) is that the CURRENT VERSION of the importer is in beta (as in it does import data) however the perm schema for 7.3 will require it to be reworked for 7.3; your best bet is, as SD said, to "beta" the importer to get your data into 7.2.2 then when 7.3 is out, upgrade to that (from 7.2).
The main reason for the permission overhaul to 7.3 is to allow more fine tuned permissions, which make "Pay-To-Subscribe" forums and "Global Moderators" a reality.
