I was using Sync for a good long while but I cut over to Summit. I couldn't get over the fact that I was paying a yearly subscription for Sync but I hadn't seen an update in 10 months while features were broken. Community posts with questions in the Sync community went unanswered.
If the dev ever ended up resurfacing, it might be worth using, but there are now plenty of non subscription based Lemmy apps to choose from. I'm not going to pay $17 a year for abandonware.