It’s kind of pointless to combo into Shippu off low shorts. Comboing into Shoryureppa is easier and it does about the same damage (the difference in damage is something like 100 dmg points). Doing c.LK > c.LP, c.MK xx Shippu seems more logical to me if you want to combo into Shippu.
Rock seems easier to pick up to me cause he’s one of the best meter users in the game. Your Shine Knuckle hits anybody stupid enough to whiff something even slightly laggy. Evac throw is guaranteed super and is pretty easy to land, raising storm is the ultimate punisher against somebody stupid enough to jump in on you while raged, and DR is like free chip that you can cancel off a lj.rh that leaves you completely safe.
Also, rock has very few bad match-ups while I’d say Kyo has a few. He’s not too hard to keep out compared to rock with that nasty lj.rh, properly spaced shine knuckle and reppuken.