> IIRC one of the Snowden documents even mentioned GCHQ and other organisations using Tor for their own purposes.

I think you're referring to this presentation about hidden services by the GCHQ [1] where they state, 'Until then... Doesn't stop us from using them'

I wonder what they may have to say about the soon coming next-gen onion services.

[1] : https://www.eff.org/files/2015/01/26/20141228-speigel-analyt... (page 25)

Yep. Tor is just a great big eye for the NSA and GCHQ. For them it doesn't matter if scoundrels use it, as long as they can use it too.