While I was in the steam room at the gym today (which, by the way I whole-heartedly endorse as a great place for day game. It must be something about the steam which makes women up for being gamed) a group of hb8's were having a discussion about their guy friend cheating on his girlfriend. I wasn't initially going to game them, but due to the nature of their conversation I just had to use Style's Two-part Kiss opener. It got me thinking though: is butting into a conversation and giving your opinion a good way of opening? Before the opener, I just said "One of my friends is going through a similar thing. Well not so similar, but..." In future sets, if i was to include myself in their conversation rather than introduce a thread of my own, would this be a good way of opening or seem too intrusive?

I wouldn't say it was intrusive, from the context you describe there. I think you'd pick up on the body language / tone etc if the conversation is supposed to be private.