I've been using it for years and years, and it has never let me down. Remember, Reddit only holds your last 1000 saved items, so manually export with this site every ‘x’ months, depending on how often you save posts.
I was a user of Sync for many years. I stopped using them and started using Cryptomator to encrypt all my data after I noticed a few years ago that Sync.com removed all references and talking points on their website about end-to-end encryption.
That used to be their main selling point for using Sync over Dropbox. I stopped trusting the service after finding nothing on their website last year about encryption except a 2018 support PDF document mentioning end-to-end encryption that hadn't been updated in 5+ years.
It made me unsure if my data was encrypted anymore, so I started using Cryptomator along with Dropbox.