I have never owned a long-haired cat. I do however have long hair myself and note that when my hair is in bad condition it lends itself to getting knotted very easily - This is due to hair becoming dry and developing "split-ends". My point is, that perhaps dietary supplements can improve the quality of your cat's coat and thus help reducing tangling? Omega oils and Linseed oils are both very good for this (in cats) and I'm sure there are many other supplements you could use...just a thought.