In my tests the modification time seemed to be totally unreliable: On most devices it is simply ignored and set to "whatever the device considers current time", or worse on Galaxy S4 setting modification time seemed to work, but after unplugging and reinserting the device, the modification time observably changed. So a "read file time after copy" may not be a reliable solution, the performance drawback of one additional file access aside.
But also more fundamentally, FreeFileSync will show files as not in sync when they have different modification times. This is after all what the user has selected, "compare by time ans size", so ignoring the time when comparison against DB entries shows no change, still seems incorrect, at least with this model.Zenju
Unfortunately MTP is just... ehm... "a poor thing" (to be polite :-) )
I can see the "why" has been developed and indeed I can see the benefit for a MEDIA PLAYER, but using it for a smartphone (can we call them for what they really are? They are REAL computers!!) is a non-sense.
Personally I gave FFS a try with my Motorola MotoG 2014 with Lollipop 5.0.1 (unrooted) and found immediately that is not usable,
but NOT for FFS's fault!!! It's the Google's MTP implementation that is really "poor".
I have searched a bit to understand why, for example, my picture folders on Explorer (I'm using Seven SP1) are different from what is really on the phone memory! I have found that Android is making a "cache" for MTP and this can be not-up-to-date!! I can't believe it... :-(
Have a look at these (some really old) bugs with "MTP" search
https://code.google.com/p/android/issues/list?can=1&q=MTP&colspec=ID+Type+Status+Owner+Summary+Stars&cells=tiles
I voted a few:
https://code.google.com/p/android/issues/detail?id=182084
https://code.google.com/p/android/issues/detail?id=95729
https://code.google.com/p/android/issues/detail?id=92635 this one is specific for FFS... "Transfering files
to device, via MTP, resets timestamp to current time/date!"
Personally I use MyPhoneExplorer to manage/backup/sync my phone data, it does a pretty good job (but sometimes it fails too on bidirectional sync!) but it use a "
client app" on Android to do its job!
I believe that without a "client side app" Zenju couldn't do more on FFS for supporting Android phone via MTP... :-(