Hmm...I have a slightly different opinion.It becomes far more natural, but I'd rather jackhammers on ANY other key, even ring fingers, than space bar.
After a month or so the spacebar becomes a lot more natural and easier to play, as if it was one of your normal fingers. (For me at least, but I don't have much experience to judge off). I always find myself now having more troubles with my ring fingers than the spacebar.
It might be dependent on the person, who knows.
But yeah, definitely stick with the spacebar. You will get used to it and it will feel a lot less awkward to play with practice.