Longhaired cats were always heart breakers for me. I had two different long haired cats, each was part Maine Coon, supposedly mat-free hair. That's true until they hit 10 years or so of age, and then both started getting mats. The older they get, the worse the mats and their skin itself is so delicate that it's easy to hurt them.
I started brushing both of them as kittens, but as they got older, neither liked it. IF you can give your cat a lion cut, i think you'd both be better off.