Besides the center of gravity varible , I look at where I'm paddling.
Going down a stream/small river at 3-5 mph with the flow and you come across a strainer and a quick look tells you that the only way to get on the other side without take out and lining is to go under a branch.
Now here is where a high seat , and especially one with a ridgit back, will or could get you into some serious trouble. Having to "lay back" , or forward, and getting under the branch without hanging up on the branch might prove to be difficult with a high seat. You might lie out in front and make it, then the seat/backed might not. Something to look at down the river so to speak.
Allen, if the tri hull is comfortable, then anything would work for ya! I was surprised to see that seat so high. It would do good in the back waters... but without a fixed/ridgit back... Then too, Harry's canoe went into some tight places without suffering. Van and Comandor's paddling showed and taught a lot.
Swampy <---- this dummy can learn a lot from the best.