Hi Dan, thanks for sharing.
Regarding your question
if it would be possible to add a field to OpenSprinkler’s Preferences page to switch between default behavior (using rayshobby server) and another URL (e.g. the server on the raspi)?
If you have a write-up, I would be happy to post it on my blog. Is it possible to share just the changes/files you made, instead of the entire linux image file? I assume a user would want to install the default Raspi image first, and then follow the change you made.