Yes!!! From a Maine Coon show/breeder perspective, slicker brushes are a big no no for long haired cats. That said, I’ve almost never seen a DLH that had anywhere near the coat that MCCs have (I’m the opposite, finally, after many decades have a DSH, everything else has been DLH and Maine Coons). Even my foster kittens that are fluffy cuteness like yours just really don’t have “long” hair like an MCC
Which is all by way of saying I wouldn’t sweat using the slicker brush on a DLH type the same way I would with an MCC.
That said, my experiences with using them is that they don’t get rid of mats or do a great job removing tangles that become mats, and if you aren’t diligent with splitting the coat to create open lines to get the brush down to the skin, they aren’t great at pulling out dead undercoat (that’s true of my double coated dog as well).
I use Greyhound combs on all of my cats. It’s just a plain stainless steel comb with half wider teeth, half narrow and the grooming standard at any cat show. I start working them with the comb when they are very young, less with the idea of combing them and more getting them used to the comb, even letting them play with it while doing the undercarriage, or rather, not objecting or punishing them for playing. I just move to a non play area when the teeth and/or claws get intense, then try to come back a few seconds later. I also try to pick nap time as training time, although kittens get fired up fast lol. My year old MCC has transitioned from indifferent to play time!!! to HELLZNO and finally back to indifferent in the last 8 mos. That’s extra helpful since he has a coat your that knots super easy. My other MCC (and my last one) falls asleep while I do the tender bits, hopefully Zevon will get there too. The easy coats absolutely needed at least monthly grooming, Zevon needs weekly
Ruty, DLH, needs a few grooming sessions 2x a year in prime shedding season just to get the undercoat off his back where it does that pre mat clumping. He could stand for more regular grooming but he came to me as an adult, and it’s just torture for him so he gets the minimalist treatment. Dear departed Vivi, also DLH didn’t need a day of grooming in her life, but she enjoyed it so she got a quick once over when the others were being done. It was helpful that not only did she not have nearly as much cost as an MCC, she was also maybe 1/5th of one, size wise.
(edited to fix a lot of dsh that should have been dlh #brainfart)