Paul, I understand what you are saying and I don't mean to say the "little things" are insignificant. But buffering data, high speed interfaces....I know what I paid for a serial-to-parallel printer converter with 64K (K!) of memory 20 years ago. These days? A $20 router has more power than a thousand dollar box did seven years ago. Does the store and forward and all the rest at gigabit speeds for $50, and that's way faster than NMEA2000 is running. As is USB 2.0.
So...I guess the only real question is whether there is any larger need (beyond jef's <G>) and whether it would take more than gluing a couple of $20 chipsets together for him to get a "sniffer" that could deal with what is still, essentially, just a serial
data flow that *might* be considered as just a slow USB bus. After all, the sniffer doesn't need to deal with the amperage levels, it can just be a high impedance device that blocks them while reading the data.
If there's a "USB sniffer" out there...who knows, that and some power protection might be enough to do the job. Not a full interface--but a working sniffer. I think we've all seen bigger rabbits come out of smaller cheaper hats.<G>
"Hey Rockie, wanna see me pull a rabbit out of my hat?!"