I did a test recently -- today! -- myself on this, and found that the butterfly keyboard does slow me down a bit compared to my usual rate, which I wouldn't hav

I did a test recently -- today! -- myself on this, and found that the butterfly keyboard does slow me down a bit compared to my usual rate, which I wouldn't have actually predicted; I'm slightly slower on it in terms of raw keystrokes and also slightly less accurate. But it's not an incredible difference, and there are other keyboards I've used (like the much-hyped Brydge keyboard for the iPad Pro) which had more deleterious effects.