By default they use 2.0 [1] unless someone or an addon disables it or unless the person is on a really old version. OperaMini however will use 1.1. No idea if anyone here uses OperaMini. There are some reader apps that act as a proxy that only support http/1.1.
replyThere are a lot of botters on HN, some that control residential and phone browser-hijacked systems. One was sending me playful messages the other day. I enjoyed the bot jousting with them.