Just to add to Todd's advice ...
If all of your users have Version 7 as a MINIMUM installation you could convert all of the models and projects to xmod and xprj files (check out the Utility Program for that) and then do a onetime change on the .bat files to bring everything up to the same file naming convention.
(Remembering of course that Version 7 users will not be able to benefit from any new features within Monarch version 8 - so be careful if and when modifying models to be given back to V7 users!)
I would imagine that would still leave you with some decisions to make about maintaining 2 versions of .bat files with different command details for some functions but it would probably be a well controlled way to go forward compared to making changes as the users hit problems.
Of course there may be other things you have to deal with that mean this approach is not possible.
I hope this idea helps.