The above is the first 5 way signed notary tx. I decided to totally change the low level transport, which ended up requiring changing one third of the dPoW code.
Now instead of using a NOTARY virtual coin, I use a nanomsg bus topology. A bit too tired to write lots of details now, but with the new bus topology, just need to verify that it can handle up to 33 signers.
I coded up a duplicate filter, but it ended up filtering out too much. So the duplicate filter is disabled for now. However, the notary servers have plenty of bandwidth so even without a duplicate filter, I dont think there will be a problem.
Still, I like things to be efficient, so I will likely improve it a bit more.