I bought the first version after 3.4.7, and updated to the latest version. The developer is very good, works with customers to resolve issues, etc. Well worth the cost to me, knowing I have a viable backup is essential for me.
It has been a while, so I can't remember exactly, but I think ver. 3.4.7 will popup a window when run on ML, saying in effect that no issues have been reported, but this version has not been tested. So, I too recommend you just buy the app, and then you will know you're good to go. 😎CCC😎
In addition, I found a bug, reported it to the staff at CCC, and the owner got in touch and worked to resolve that issue in short order, which was incorporated in the next version after 3.4.7. I am sure they have fixed countless other issues up to the current version. Get that, use it in demo mode for a month and decide if it's worth it to you to buy it.