I think how well a pyramid design performs depends on how you define performance. If you only look at fps, then among straight-stave bows with no recurves or reflex, a pyramid is a superior design (in my opinion). My fastest straight-stave bows have all been pyramids. But with any design there are trade-offs. If you want a straight-stave bow and you choose to maximize fps, some other factor is suffering. For pyramid bows, in my mind one of the factors that suffers is the longevity of the bow. You're stressing the mid-limb of the pyramid bow so that it's about as efficient as it's going to get, but that means it's under more strain and the wood fibers will break down sooner from that strain.
Although they haven't been quite as fast, I've gravitated more towards paddle bows as of late because the wider mid-limb seems to buffer the bow against excessive strain a bit better. I'm willing to sacrifice a little efficiency in favor of a bow that maintains its performance longer.
But that's just me, of course. Others are free to make their own trade offs.