There are many times a client doesn't allow personal equipment or software within their business. Web Access would be an alternative.
Maybe you could just have the ability for the user to download the TT&A file so they can keep their own backup with a disclaimer that it is up to the user to save their latest file as a backup as there is no guarantee for the online data. Then just add the ability for the user to upload their data file to replace the online data. This way Magsofwrx won't have an administration nightmare.
I wonder how many consultants are as restricted as I am when it comes to using 3rd party software at a client site? To me, this would be worth the risk of handling my own backups.
Thanks for considering it though!