For the security aspect, I've skimmed through the code, it seems the "building blocks" that they are using (security primitives) are still relevant as of today. Namely I've found AES, ed25519, Hmac. The code itself is mostly taken from Text Secure (now Signal) at a point when they've decided to drop SMS support in order to focus on their own network (bypassing SMS). Personally I'd trust it more than raw SMS at least. I think I'd mostly trust it. I use Element/XMPP/Signal mostly though. In fact I've stopped using Silence few years ago.. Somehow thinking outside of the SMS box now.