Related to the GTK2/3 thread from last year, I am getting more serious about
the OS upgrade I've been putting off for far too long. The change in direction
for Ubuntu's desktop has left me in a quandary as to which OS to choose. From
what I've seen, it is unlikely I'll be satisfied with Unity. It'll definitely
be something in the "Debian universe", but it could be an intermediary version
of Ubuntu that still supports GNOME 2, the latest version running GNOME 3, the
GNOME 2 fork,
MATÉ, or
the GNOME 3 fork,
Cinnamon. The
latter two being primarily supported on Mint, but apparently there are Ubuntu
packages available. I haven't evaluated either, but both were born out of
dissatisfaction with Unity and GNOME 3, so they are likely to be a less
painful transition from a tuned GNOME 2 environment.

Short of trying each option and living with it for a while, which isn't
particularly practical, there isn't a great way to compare the options.
Switching OSs is a pain.

In any case, one dimension of this will be application compatibility, and I'd
prefer to continue using Roxterm, which is one of the top 2 or 3 applications
I use daily. Which of these newer platforms has Roxterm been shown to
successfully run under?

ROXTerm should be fine in any desktop environment. You have a choice of GTK2
or GTK3 at build time or by choosing a package from Debian experimental or my
Ubuntu PPA. It has a good track record in GNOME 2, and I now use it regularly
in GNOME 3 on my laptop and in XFCE4 on my desktop (where gnome-shell
developed a habit of crashing). The only issue is the geometry going wrong
after one-way maximizing in XFCE, which is a bug in xfwm4's workaround for the
GTK3 bug #649680. I
haven't checked whether this xfwm bug (I can't find it now in xfce's bugzilla)
affects the GTK2 version as well as GTK3.

The next version will be "unstable" rather than "experimental", where it will
automatically migrate to "testing" etc, but I doubt this will happen in time
to be synced to Ubuntu's official repositories. 1.22.2 works quite well
though, subsequent releases have mainly been about GTK3 support and the new
bespoke build system.

Just to follow up on this old thread, I ended up going with Cinnamon on Ubuntu 12.04, and Roxterm has been working fime (except for some minor issues reported elsewere that don't appear to be desktop related).