[quote author=Coding Badly link=topic=241103.msg1733717#msg1733717 date=1400721666]
Bear in mind the protocols are designed for high speed manufacturing where communications problems would have been reduced / eliminated out of necessity.[/quote]
I should imagine that's the usual rationale, however bootloaders use serial comms links, and there have been fairly robust file transfer protocols for decades, eg, kermit, x-modem, y-modem, and a dozen others. Small packet transfers with checksums and handshakes, etc.
In any case, got any ideas on the reset-sync problem? Any -options in avrdude to change the sync-up business?