I didn't know you could separate dd like Steven suggested - that's pretty cool.
I'll add two ideas:
1. I think cp can make a block copy, if I'm remembering correctly with that, you might want to see if scp can do the same.
2. You could do
... of=/dev/tcp/ip/port
(IIRC) on >2.4 kernels and get nc to catch and pipe the output. Don't know how you'd deal with simultaneous uploads there and check for the new connection to figure out where the start and stop of the dump was, but...