No if the usbstick is formatted as ext4 windows will imidiatly ask to format it and you can not backup using win32imager because there is no drive letter to choose.I don't think you can do that ( the 1st part) , at least i cant
My win7 pc cant natively see the USB drive once its been formatted in ext4 format. However, I take a back up of the usb stick by using MiniTool partition in win7 which can see the usb stick , and can make a copy of the storage partition which i copy over to a portable hdd ( or a spare usb drive of equivalent size).
Use the backup function in openELEC settings. Move backup file to new system and restore. Done.