R.E.D. from burton apparently s**k, protec and others dont really have good reviews or have inadequate padding/protection.
My wife wore R.E.Ds while she was learning and they did the job just fine. I don't know that I would want them for more extreme riding, but she didn't complain much after I got her a pair. Now they sit around collecting dust so keep in mind if you buy something expensive you'll get maybe a season of use out of them unless your s/o goes crazy in park.