The key word is "easier". Not "effortless". And it definitely is easier than building fat clients for every major OS (which probably is why they didn't bother to try with anything but Windows in the first place). For me it's not the GUI in itself so much, it is the mindset behind it. And I don't blame the developers, I blame (product) managers - until proven otherwise. I definitely will switch to SyncThing/Pulse as soon as it has all the features I need, unless BTSync does a radical change (like going open source and/or really letting the users decide what features to concentrate on).