In EP, I'll sometimes (very rarely) limp a premium holding (QQ+) with the intent of inducing a raise so I can RR. I do this only when I'm virtually certain to get a raise behind me. This presupposes that I have reads on individuals or the table just doesn't ever allow a limp around. However, I also play 25nl so what works at 400nl is likely different. I mainly do this if the cards have made me very active for a stretch. It's a changeup from my normal play.