I'll give you a few thoughts from a user's perspective. I have ambitions of learning python and qt and doing a few things, but I am a looong way off.
BTW, if this were the desktop linux world, we wouldn't be having this conversation.
As a user, what do I care about:
Applications - I need to do what I need/want to do. On the desktop side, it doesn't matter what distro or window manager I choose, in general I have access to the same applications. And if I choose carefully, I can use the same applications on linux and windows.
In general, as a user in the desktop world, gnome versus kde versus something else; rpm versus deb; apt versus yum versus something else is moot. In general, I can do the same things or get the same functions lots of different ways . . . again it's taste.
So, on the zaurus, if I have all the applications (or reasonable alternatives) that I need and work on all the distros, then it comes down to a matter of taste. I don't think we are there yet. Although, among the applications I use are KOPI, KAPI, Portabase, Opie Reader, and Bedic -- all of which are available on OZ/Opie, PdaXrom, and Cacko.
I still like some Sharp ROM based apps that seem harder to get usable on Opie, or require closed libraries. Similarly, I quite like some Opie apps (e.g., Dagger) that don't seem available on Sharp ROMS.
The System Doesn't Get in My Way - Different people are more comfortable using different systems, so again there is an element of personal taste.
As a user, the keyboard repeat rate with the OZ 2.6 kernel got a bit frustrating. And as a user, I don't know how to fix it to suit my tastes. Typing faster as the kernel notes stated didn't make the annoyance go away.
The System Works with My Stuff - This is actually my key criteria in selecting a desktop distro. Does it recognize my hardware and peripherals or is it relatively easy to set up?
I have an ir keyboard. To be the most productive with my CL860, I would like to be able to use an external keyboard. PdaXrom (which I like) doesn't seem to support this. On Oz 3.5.3/Opie I couldn't figure out how to get it to work (IRK depends on lirc which didn't seem to be there for the 860 -- maybe I'm wrong).
It Should Be Fun to Use - For me this takes a backseat to being productive at the moment, but it is an important criteria.
Conclusions -- I personally think that OZ is the future in that it is device, vendor, and x-server/framebuffer agnostic. It will also support more devices.
Rather than Qtopia updates -- maybe we need to focus on QT/E updates.
PdaXrom also has a special place in my heart. If I could get the PdaXrom experience on top of an OZ base that would be cool.
But the "ROM" I find myself using the most is Cacko -- even though my view is it isn't the way forward. The reason I use it is because it just works . It has broad compatibility with existing apps -- many of which don't seem to like OZ/Opie. And for what I do, I tend to be the most productive in it. For X-based apps, I can use Debian/X-Qt.
Commercial and closed source programs without good free alternatives may continue to exist -- but if somebody can get them to compile for OZ/Opie too, than we can move closer to the best of both worlds.