It would have been awesome if the RS made him a lot stronger but made him loose his emotions like his bros. And he would have begun to attack his enemy and killing them and also hurting friends who would have been in his way (like Nami). That is why he would have chosen in the end to destroy it.
I think it's quite clear Denjiro is the strongest Samurai by far right now. I have him as at least King level if not stronger. Ashura was on that ship and he was shitting his pants like everyone else. Denjiro is SOLOING those ships.
This dude was gonna be Oden's First Mate and is the head of the Yakuza like Hyo. Kaido feared Hyo and Oden teaming up.