I agree it's a good indicator, only given it isn't exclusive to a restricted platform (or expensive platform, therefore making it a status symbol). I think Signal does this right, 1. by supporting all major platforms, 2. by showing standard SMS as "dull grey" and allowing you to choose your own color for a contact (otherwise having a random color) when the conversation is Signal enhanced. On that note, I have hopes that Signal can become The One True Messenger after they iron out a few more quirks.