Is it safe to use SPDY implementation at that point? I've seen critical flaws in the past...
The switch to HPACK for header compression resolved this. SPDY/HTTP2 has no currently known security flaws.
https://github.com/18F/tls-standards/blob/master/configurati...
When SPDY 4 or HTTP/2 make their way into an nginx module, we'll upgrade, and turn header compression back on.