I've had the carpets professionally cleaned a few times here, and I used the rake, then someone else with a really good vacuum cleaner went over all the carpeted areas. The guy who came to do the steam cleaning was impressed, and said that not enough people use carpet rakes, and he wished more did. It was better for the carpet and made his job a bit easier.
Maddy's been shedding a lot during the past few months, and it looks like a disaster. I just rake it up, though, and it goes in the garbage.