Clarifications for merge workflows

Hello,

Some informations are available in the manual about distributed content
management workflows.
http://kernel.org/pub/software/scm/git/docs/gitworkflows.html#_merge_workflow

I find that a few details are missing to achieve a better understanding for the
merging of branches.

Use case:
A contributor pushes an update suggestion from the personal repository "ABC" to
a topic branch in a public repository "SHARE" on a separate server. An
integrator reviews the proposed changes. If they are accepted, the integrator
will choose a repository where the merge should be performed next.
- Log-in to the server and integrate the updates there.
  or
- Fetch the remote topic branch into the integrator's own local repository
"XYZ", merge there and push the result back to the server.

Which ways do you recommend to select the storage location where a merge will be
applied first?

Regards,
Markus