I have Eastern European heritage and PCOS...it is safe to say that I was pretty darn hairy for a girl. I had a series of laser treatments (4-5 sessions) about 8 years ago, and here are my results (no treatments since)
Face: Upper lip, chin and front of neck. Hair growth never went away completely, but it is approximately 30-40% less than before. Still enough that it must be dealt with daily
Under arms: Hair growth mostly went away, but began slowly returning after about 2 years. Currently, I would say that my hair growth is about a quarter or what it was before.
Legs: Only sporadic hairs growing even 8 years later. I shave about once every 6 weeks in the winter, and about once every 2 weeks in the summer.
Around nipples (hair was fine to begin with, but still a bit embarrassing): No regrowth, don't have to worry about it any more
I was too embarrassed to get my belly or pubic region lasered, but the technician did tell me that as part of their training, they did laser on each other. She basically had a brazilian done one time. She said it was incredibly painful, but that her pubic hair was much softer and finer for years afterward.
My two cents (with absolutely no scientific knowledge to back it up

), are that us lucky PCOSers have hormones telling our bodies to grow hair where ladies usually don't have hair. Based on my regrowth, I would say that those hormones are winning with regards to face, chin and front of neck. However, the laser was very effective for me on the other areas (where most women have hair growth)....