I see I haven't replied yet to your first point: here goes. Of course clearly an alternative has to be at least cryptographically secure. I fully agree with you on that. I'm not recommending something that isn't, and certainly am not recommending Telegram or Cryptocat.

An alternative needs to be as a bare minimum cryptographically secure. And then on top of that it would be very nice if there was federation, not tied to phone numbers and all the components being open source. Those last 3 points is where Signal fails currently. Federation is something that moxie tried, didn't work out, now he's basically not in favour of that, the phone number issue is of course well known, and the redphone server component is not open source.