Adding my appreciation for the plugin – it does what it is supposed to do, and no extra clutter.
A few thoughts on the UI (in Settings>General)
1. I, along with other posters, think a separate page would be useful. My feeling is that it would be easier for a user to locate the plugin settings. It wouldn’t need any more info than what is currently in the Settings>General area. You could locate it in either Settings, Plugins, or possibly Tools.
2. When selecting ‘No updates’, the ‘Advanced’ option ‘grays out’. This is confusing (at first, I thought I could not perform settings). Suggest that this NOT be grayed out at any time.
3. ‘Advanced’ again: suggest you leave ‘Advanced’ Visible at all times. It is not a large section, and always displaying it reminds the user of those options.
Great work – I can’t imagine running any client ‘production’ sites without disabling automatic updating.