A Furminator "cards" the coat by scraping over the topcoat and grabbing onto dead hairs in the undercoat. They work OK but great care must be used so that you don't scrape it over bony areas, as you can cause an abrasion fairly easily. It works mostly for body coat, and I doubt you would be able to reach underarms, between legs, etc. You still need a good comb IMO.
I groom for a living, and my cat tool of choice is a good quality "greyhound comb". Metal, fine toothed on one end and medium on the other. I also use slicker brushes quite a bit on my own cats.
Zoom Grooms work, just the same as a rubber curry. I still think a comb goes deeper, though.
I have the Furminator, and I love it! More importantly, JinJin loves it! I brush her for just a few minutes each night. Initially I was getting handfuls of hair out of her, now it's just a bit each day. When I'm done, she rubs her face and chin on it.
I bought the Furminator at Petsmart. 40 dollars for the small one 50 dollars for the medium and 60 dollars for the large. They are miracle workers on my dogs, I know that for a fact. That case it was well spent, for cats....I dont know, I think it would work better on long haired cats that shed alot.