The download link you get with patreon is to itch.io, and I remember some extra files: an older engine download, and a more frequently updated download that doesn't include any engine. So with Patreon, if development starts back up, I think you'd get more frequent updates.
You don't need to pay every month to keep your permission to download the game through itch.io, not unless there's a price hike or something that would disturb that.
The Patreon's paused right now so you wouldn't be paying every month in either case. I used to follow Patreon updates and have a purchase through itch.io now, and I haven't noticed any differences.