[halomru]

>This is because of the widespread assumption that anything that goes over port 80 is HTTP 1.1, which makes some middle-boxes interfere with or destroy traffic when any other protocols are used on that port.

I'm not convinced that's a real problem once traffic leaves your servers/CDN. In practice I have seen lots of protocols use port 80, since 80 is the port that's most likely to be unrestricted on even the strictest corporate firewalls.

[noselasd]

It's a real problem. There are plenty of middle boxes around either at ISPs/cell operators or in residential gateways/modems that interfers on port 80.

[danudey]

We make mobile games for iOS and Android, and we've mostly switched to HTTPS because of people injecting garbage (ads, mostly) into our content.