You'd have an exact replication of the Zoro vs Ryuma fight.
Speaking of that fight, it's the perfect example of why skill matters. There is a point in the fight where Zombie Ryuma, uses one of Brooks thrusts attacks, and it ends up causing a piercing blast through the concrete. Upon seeing it, Brook replies, that he has never had that effect, when using the exact same technique. He then goes on to say, he didn't even know you could use a thrust like that.
So here we have two people, using the same exact attack, and one of them uses it way better than the other one, and the other one being shocked that the attack could be used in such a way. That is 100 percent reflection of Ryuma's skills, and Brooks lack there of. It has nothing to do with Haki, or strength. It was completely skill based.
And not for nothing, but Vista can match Mihawk blow for blow in physical strength. So would that mean if we did the same scenario as before, with removing haki, and replacing Mihawk with Vista, then Vista should be able to neg current Zoro with a pin knife as well, right?