:D It's not my first rodeo doing high speed design. > 2. If you want to run an interface faster than a few MHz, you have to be more careful on the electrical l

:D It's not my first rodeo doing high speed design. > 2. If you want to run an interface faster than a few MHz, you have to be more careful on the electrical level to avoid reflections/impedance mismatch and other signal integrity issues. Essentially, you can't just hook up 2.54mm pin headers at gigabit speeds and expect everything to work fine. Conversely, we got a gigabit out of a few wires, non-differential, on pin headers UltraDMA/ATAPI over distances of tens of inches, albeit with the insulation displacement connector able to put a ground between each wire on the ribbon to lower impedance a bit. It would be nice to have some more capable interfaces multiplexed onto the pins. That's all I'm saying. For that matter, an RJ45 doesn't have wonderful electrical characteristics, but it's a small impedance discontinuity at the ends of the circuit. Industrial uses put gigabit ethernet through all kinds of connectors. Gigabit Ethernet works in practice through a few inches of untwist and would work just fine through a pin header. Already not everything on the header is hooked up to a single GPIO controller-- some goes directly to the broadcom and some to an external GPIO controller on earlier PIs, I believe.