I did it once with a Motorcop, at the end of September I was coming down I-25 and there was a huge accident @ 84th ave. A Motorcop came up "lane sharing" and waved in behind him and helped me get through all the damn backed up traffic it wasnt too bad but then again everyone was moving over anyway hehe, gave me a thumbs up once I was cleared to exit at 84th with everyone else but at that point I just continued till I got to the light then merged in with all the traffic . I take it he was probably from Cali! Haha
Oh, and No, I would not do it on a regular bases, Emergency Situation, like I'm about to get hit from behind For sure, but just to get through traffic faster, Nope, not for me! Besides the fact it's illegal I just wouldn't feel comfortable. IMO