As for the K3 devices: I've been trying AdvancedToolkit on my K3 Wifi - and wasn't successful. Might be because I was handing over USB2 traffic to a Windows XP running in VirtualBox, though. But it recognized the MX35 in the USB Downloader mode. However what didn't work was dumping the MMC using that approach. The flash tool just told that it wasn't successful to bring the device into the right mode.
Maybe it doesn't support dumping MMC contents? Then it might only be bad timing because of virtualized USB2... I've not yet looked into the Freescale data sheets whether it might be write-only, but that's a quite common feature on microcontrollers...