conda-build-all can copy from one channel to another: `conda build-all --inspect-channels conda-forge --upload-channels astropy some_packge_recipe` will copy the `some_package` from the channel conda-forge to astropy if it can, or build it if it doesn't exist on conda-forge. Discussion about what the desired behavior should be has started at: SciTools/conda build all#46
IMHO, if it's just one author in staged recipes, sure. If feedstock, no force push - only to PRs to feedstock. If people don't mind merge PRs, it sure is a lot simpler to not rebase. I have messed up rebasing a few times recently... =(
There have been improvements on Continuum's side that should help this. In short, repodata (the package index for a given channel) was being generated for each anaconda.org query. This was unnecessarily high cost, and some caching schemes have been implemented.