I have a knock off that I got from Amazon - for my double coated CAT - not Brodie, I would NEVER use it on Brodie! Although Caro's post on the poop shoot - I might try that one to see the difference between it and a scissor cut - on my list for this week!
I do use the knock off furminator quite successfully on our cat. Understand he has a thick, double coat but his outer coat is short, just a tad longer than his uber thick undercoat. Every few weeks, we go out on the deck and he gets a thinning out. Goodness, I could make pillows with the hair I remove from him! But it is NOT grooming - it actually cuts the undercoat. With Rusty, it may even cut some of the outer coat but it does work very well - for him.... He is an indoor cat, is only allowed out on the deck for his grooming and is on a leash then so no fears about him needing that coat for heating and cooling.
I would never use this on Brodie....