Note: This post was wrote 2 months ago and never published, my bad.
After some bug squash, I finally got p2p transfers working. I have tested sending and receiving custom emoticons and display pictures, smallers than the SB limit and bigger than that. They just work ok.
I guess I need to test some file transfers before thinking my work is done, I also have some cleanup that I want to do but I guess I can declare that the new stack is working nice and is very close to be merge ready. I'm really glad to say so.