Harry, both boats are regular big kayaks. You shouldn't be wearing tevas or other big shoes anyway so with neoprene booties or water socks you'll fit in fine. Yes your toes will touch the deck when pointing straight up but there will still be plenty of room in a normal paddling postion. The AH high volume version sounds interesting but 16cu.ft. is way big if you aren't loading it down, who knows maybe it's the one but 13.5" is a tall deck.
You didn't mention your paddling experience but the slightly greater primary stability of the Coho might be more pleasant if you're new to paddling. My $.02 is that four-panel hardchine boats turning characteristics are a personal preference. If you can get the turning characteristics you want with a smoother shaped hull it's going to feel more predictable in rough waters (less twitchy).