RE: CD1 without a network mirror isn't sufficient to install a full desktop environment
Just a quick suggestion. As a compromise, instead of enabling Xfce as the "universal default" in tasksel *entirely* ... How about only enabling Xfce as default for the CD* distribution, and leaving the default as GNOME for all non-CD distributions? (DVD, netinst, ...)
That will express true "bipartisanism" ... instead of explicitly being biased towards one direction or another simply at the whim of (a) certain decision maker(s), especially over a technicality. Yes, you can argue this might incur a "split" between install bases and, thus, possibly be less "easy" to support ... But both GNOME and Xfce are officially integrated into Debian, and so should both be considered equally ...
GNOME has a longer-standing status, specifically with Debian, and other GNU/Linux distributions at large. It's also an officially-supported GNU project, as well as being more "authoritative", in the sense that it's the base of GTK+ which is utilized by Xfce.
According to popcon, Xfce is more common on Debian than GNOME... And considering the recent controversy surrounding v3, many have opted for alternatives such as Xfce, MATE, Cinnamon, Unity, or etc... I, personally, feel as if GNOME is sort of going the "KDE path" as far as becoming somewhat bloated. Xfce's lightweight-focused approach can be appreciable, but modern high-level functionality shouldn't necessarily be compromised by lack-of/restricted resources. Simply the fact that it's an OPTION is terrific. But, from the premise of this entire letter, shouldn't exactly be *forced*.
Thus, I reiterate that it might be a good idea to maybe consider the possibility of thinking about the potential for ...
Xfce being set to default tasksel in CD* distributions, while GNOME remaining default in others.
At *least* as a compromise during a ``transitional'' period, whereupon the eventuality of settling on a single/unified default may come into play yet once again.