In case of the 7 version:
AFAI can remember you do need to pay for using the versioning and there is just one (1) moment to activate it.
Version 7 does indeed use a sort of 'soft-checkout' that is pretty annoying.
Versioning is pretty cool when you need to migrate a new version from testing to - say - production. In version 7 it was not perfect,but quite usefull.
Keep in mind that using versioning will have a profound effect on the repository. You need to take into account that metadata reporting by any tool addresses the proper active records.
In any case you need to make up your mind BEFORE starting, you cannot switch to versioning halfway..
Ties Blom