Hi Adam,
A lot of thanks for the stunning investigation you made! I still can't find 10D sample to test myself. Your findings are very interesting! Mine showed that Digic 1 doesn't accept command to set Bulb speed, but obviously with your interaction with camera you somehow confirm Bulb and this allows plan to be executed.
During my attempts to make APT working with 300D I put a new quality option in plans, named "custom" which doesn't attempt to change the camera quality and uses directly the manually set value (but it still has to be JPEG quality
)
Interesting finding is that ISO change is making also problems
. If you want I can send you a version in which exposure change is skipped for Digic 1 cameras. In cooperation with the "Custom" quality, it will be able to track down if ISO change is working correctly or not.
The idea is to make a version that allow Quality and Exposure to be set manually from the camera (or with other words to avoid the limitations of Digic 1) and then to execute a plan.
Please send me as PM an e-mail where I can send you the test version.