I’m struggling to find where I heard about this, but if you post to Twitter (or I guess it’s X now) and tag @Sync, they should get back in touch with you and offer you a bonus 10GB for the positive outreach.
Since I don’t know about where I heard about the offer originally, the next best thing might be my post which Sync responded to as evidence of the bonus. Along with one or two other bonuses which one may have been a referral, I’m at 17GB on the free account which is pretty decent, and certainly not as burdensome as the referral process one has to go through with Dropbox to grow the free tier there.
They’re a great service from the time I’ve spent with it and worth a go.
I think they’re a bit damned if they do, damned if they don’t, given a lot of users are clamouring for these features however the TestFlight is full so new users that want to be on the bleeding edge can’t get in.
There was talk about removing test flight users that weren’t actively using the app, unsure if they’ve pursued that and if that’s the way forward, but it may be a short term fix if it is available.