The only push-back I have on BJJ (as I practice both KM and BJJ) is that there is a huge sport-orientation whereas KM, assuming trained competently, is a combative system such that you'll often get a "practice this slowly and carefully because you can and will cause damage to your partner."

Personally, I have a little harder of a time training BJJ for the reason that everyone thinks it is the best for real-world defense but the reality is many moves open you up to serious maiming in a combative environment. Take for example the typical "get past the guard" move, I most always have the option in a true fight of grabbing your knees and splaying them outward leaving you with an unfortunate convalescent leave, perhaps permanent injury.

More generally, if you're going for true-blue self-defense any sporting-oriented art is good but not great - you'll do well against an untrained assailant, which is likely a good chunk of the threat model.