Another bit of labour saving advice that I’ve just started using…
There is a function is the ASF called reset_do_soft_reset()1, that will soft reset an AVR32 (not that suprisingly!).
You can use this to avoid having to power cycle your whole modular system to flash the AVR32. In fact if you use a very very long press on the front panel button to activate the soft reset, the device automatically comes up in DFU mode by virtue of the front button still being held.
Combined with the autoflash.py script I posted earlier, you can get a pretty smooth development workflow.
The only thing that would make it even better is if @scanner_darkly’s two > one worked with the DFU cable as one of the devices.
1 see libavr32/asf/avr32/drivers/cpu/avr32_reset_cause.h