Would prefer sending to 2587623823894059467[check digits] when I need to enter the entire address and unable to use aliases, and sending to John, or John276, or any other alias of my choice when I can. If I use alias, I do so accepting the consequences of mistyping. I think most regular folks would also feel like this.
726 in John726 is the CRC-sum.
Well if someone registers all possible typo's of that alias you can still send to another account by mistake, right? So crc seems useless unless it's enforced for all aliases. Perhaps with some kind of pre-text: crc:john726