I think it would be a very good idea to focus all efforts on getting Ubercart 1.0 out the door. The port to DP6 will be much easier as well if taken from stable code. I'm not suggesting waiting until every bug is fixed -- that never happens anyway.
Ahh, my sentiments exactly. Also, very keen to point out the security and stability requirements shops will have. A closer examination of CCK/Views will also show that neither are out of alpha yet, and it will take longer for Views as it's combining the D6 update with a version change.
Assuming no major bugs, I'll be putting up a release candidate soon. Once we get the 1.0 out the door, the effort to move to D6 will get under way.
Regarding my modules you listed, I'm actually going to try and leave behind uBrowser and TAPIr, but I haven't fully planned that out yet. 
Joined: 08/07/2007