Rab,
FTP sync such as you describe, where you put a copy of the Windows data file on an FTP site of your choosing, (I have done this in the past), will not work with Android. The data file formats are different. This is the same situation as the Pocket PC version, which uses a different file format than the MLO Windows application. People asked for the apps to use the same format, but it was not possible at the time. This does work for syncing two desktop machines running MLO however.
Wifi sync allows you to sync your android file with your local pc Desktop file via a wifi network. Both devices have to be on the same wifi network, such as your home network.
MLO Cloud is the solution that will allow your Android device to share data with your Desktop file. The IOS version can use this solution also, and so you can now share data with your phone, your Ipad, your desktop etc. It certainly gives people some choices.
From a timeline perspective, first came FTP sync, then WiFi sync, and shortly after, MLO Cloud, so part of this is MLO's continued development, as well as Andrey's desire to help meet people's syncing needs.
Hope that helps.
Phil.