a. staying with API 1 ?
Every now and then, I made a copy in the Finder, into a backup projects folder of the current state and I append the date to it for future reference(s).
This seems, IMHO, a good idea with API 2.
b. Changing Xojo to a new version ?
IMHO and if you can do that (there is n workaround you are waiting for in a new version): always stay with the actual Xojo version until the project is done. You will upgrade before you start another project. Two “good reasons” (also IMHO):
a. this keeps you away of bad things that can appears sometimes after a new version is released (we alread saw that in the past; this is not a rant, just something that can happens, sometimes, rarely).
b. even if the new release does not have troubles, you may reach slowdown because of changes (even good changes): we most of the time have to ‘waste’ time to adapt to the new version and if you have a project running (/ near the release time), you cannot slow down the development.
As usual, this is my opinion, do what you want, what you know is better for you.