USB3: There are still compatibility issues with usb2 devices plugged into usb3 depending on the physical controller and kernel used. So I'm not surprised to hear there are problems. This is low level and not related to mtp.
Copying folders: Yes, this doesn't work, due to how Nautilus handles the operation. It should internally transform it into mkdir and individual file copies, but it does not, and it's not possible for a gvfs backend to sanely emulate this behaviour. I should change it to fail the operation, rather than make an empty directory. It's on my list.
Moving files: This is an optional feature in the MTP spec and no device supports it - the only thing you can do is move to PC and back again. Yes, it's ridiculous, but there you go.
Mio,
USB3: There are still compatibility issues with usb2 devices plugged into usb3 depending on the physical controller and kernel used. So I'm not surprised to hear there are problems. This is low level and not related to mtp.
Copying folders: Yes, this doesn't work, due to how Nautilus handles the operation. It should internally transform it into mkdir and individual file copies, but it does not, and it's not possible for a gvfs backend to sanely emulate this behaviour. I should change it to fail the operation, rather than make an empty directory. It's on my list.
Moving files: This is an optional feature in the MTP spec and no device supports it - the only thing you can do is move to PC and back again. Yes, it's ridiculous, but there you go.
Thanks for the feedback!