Would recommend, however In my experience it has taken a long time to convince some friends to use anything over FB,SC, and SMS. Most still won't and I simply refuse to answer them. They don't see it as any different than the other 4 apps they already have to chat from. That being said I have found it a bit easier in a "first time" meetup experience to convince someone to start using something like signal assuming they want to keep in contact and that's the only option you give them.
Discussion
That's what made me consider this option. Because cutting people off after they text me is a lot harder than them choosing to just never contact me by not using Signal. It's also harder to convince someone who is already talking to you through SMS, at least in my theory here. It sounds like you've tested that theory.
Exactly that! In my experience people don't like the coerced change. If it's new I've had slightly better success. Plus I think phone numbers can seem a bit more personal, depending on the interaction. I have also had success with group chats lately.