Well dulwich, can be used for one of two things :
  - 1. Writing local tools for automating git
  - 2. Or writing services needing to automate git their workflow (for example writing a github clone in Python or whatever)

I do believe that the Paramiko vendor should be the default/preferred one, since it is more feature complete (it can also look up local keys by adding the ```looks_for_keys=True``` to the kwargs), and it can do flexible username/password auth which ```SSHVendor``` can't do.

I do feel that as such the warning is relevant. But as you mentioned, for those using dulwich for local workflows  ```SSHVendor``` should suffice.

Let me know what you prefer, and I will alter/remove the warning accordingly.

PS: I've got some commits I'll be adding to this PR in a few minutes (which tackle the other concerns you raised), I would really like to have this merged into dulwich's master, given that I have now published ```gittle```, a high level library on top of ```dulwich```. So ideally I would like it to depend on dulwich's master rather than my fork.