Both sites are working on it. export your follows list in json and csv for now. Having all 4 files can't hurt.
From my current knowledge, mangadex dev is prefering csv and manga.sh dev is preferring json.
There is some sort of 3rd party method for importing follows on mangadex but its not offical and i heard it takes some time.
https://www.reddit.com/r/manga/comments/7s45q9/import_your_batoto_follows_into_mangadex_with/
Haven't used it myself since 3900 follows would take quite some time, but ppl have said it works for them.
Updates have already been slipping the cracks unfortunately.
Mangadex's batoto data is from Jan 15th or so.
Thank you so much! I have only 650 comics so I should be fine, probably. Hopefully you'll get everything in order too.
It's a shame about the lost updates, but I've been trying to catch them. Never before have I related to someone from the gold rush so much :')