Coolest thing I've done? Yeah, I've landed on stuff. I've shot people down. I've even figured out heli's to an extent.
The coolest thing I've done in G5 is learn to fly the P-51 well enough that the guys thought the trainer was flying his plane while I did multiple touch and goes.
"heh, we though ole John was flying. You like those two wheel landings to were doing over and over?"
"eerrrmm I don't know. I thought I was just landing. Are two wheel landings bad?"
"Nah, actually they're alittle harder, especially for someone new...."
Win. Not a huge win, but a solid one as I see it.
Oh, yeah, that and I recognize more pilot errors in videos then I did a year ago. Mostly because I've experienced them in sim. I'm not saying that I wont make an error here and there, but it is easier (cheaper) to learn from other's mistakes due to simulator knowledge.