> People who have chosen to use pkg[src] (and I mean just the release
> "versions") have implicitly, if not even explicitly, agreed to upgrade
> their packages when they upgrade their base systems.

Oh really?

Let's see, I have 193 packages installed on my machines (various
hardware platforms).  I update the base system about once a month.
Funny that in all of those upgrades, I continue running the old
packages for several days and have never seen a problem related to
that.

> The very use of third party shared libraries
> in any part of the pkg system guarantees that upgrades must sweep across
> the board.

Pure hogwash.