Well the NethForge is a YUM repository, now enabled by default on NS7. From my point of view the biggest difference between packages from the (let’s call so) Core and packages from the Forge is the latter are not officially supported by Nethesis for their products. Thus the new repository for sogo is not temporary: it reflects the company choice to support WebTop as groupware.
I worked hard to provide packages.nethserver.org to this community, in the effort of implementing an open development process. I hope developers will choose the Forge to distribute their packages.
I think the @quality_team is here to help developers on verifying what is published is good, no matter what repository will serve it.