Recently I failed to reply to an urgent text about a medical diagnosis from my fiance due to Signal failing to push the message to my phone. This is unacceptable behavior from a critical application.
Do I get on a soapbox about how surveillance is terrible and miss being there for her by insisting on using Signal? No! I want her to be able to get in contact with me if there's an emergency, and that's the #1 priority.
in the situation you describe, or any urgent situation where speed of communication is paramount, what about bombardment through multiple channels? like, i'll often leave my phone out of my pocket, and not pay super close attention to it. and if it lights up with one text message, or one signal message, or whatever, i might not look at it. but if it's buzzing like crazy, or someone starts calling, i'd pick it up.
i guess what i'm saying is, "urgent" to me means signal/text/call/call someone that might be around the person/whatever, until the message gets through. if something is urgent, i would not send it solely by text. i've certainly had SMS messages get dropped or delayed many many times over the years.
can you really only use one messaging app at a time? signal is my primary messaging app, but i don't really find it bothersome to use whatsapp and regular SMS also. different people i communicate with prefer different channels, and often the same person will use different channels with me depending on the purpose (e.g., my dad mostly chats with me by SMS, and most of my immediate family's group chat is on SMS, but when my dad is texting with me about some sensitive personal financial info, it's over signal).
also, i hope that whatever the urgent issue was, it was resolved in an ok way. like i said, not trying to shortchange the urgency of a medical emergency or second guess your decision making or frustration at the time.
That's funny, I've had the opposite experience. Once I got everyone I know to start using it and was completely locked-in, I started having all kinds of weird issues.
My favorite is when my phone has been off awhile. After I turn it back on, I get a notification for every message I sent/received on another device while it was off. Usually takes about 30 minutes for it to fully sync, buzzing and/or producing popups for every message along the way. I have about a dozen equally frustrating issues I could, if I had the time, enumerate.
And of course because it's free, there's no real support. Signal has been a huge disappointment for me. I'm preparing to move back to regular SMS, but now I have to untangle all of the users like my mother that I convinced to use Signal. Caveat emptor!