I have both of these gaiters and IIRC the height are about the same on my leg. I'm 6-1". I prefer the Stormfront gaiters but the FL ones are nice as well
I would highly doubt the first lite would even get around your foot and calf. I have big calves and size 14 feet, Bramblers or the short first lites and any first lite socks just are not an option due to size offered. I tried on the first lite gaiters a few years ago with tennis shoes and they wouldn't fit.
Sitkas are nice, any reason for steering clear of Kuiu Yukon? The Yukons are about as quiet as you can get without something like the Kenetrek fleecy covering that picks up water.
I have large brambler gaiters and they struggle to get around my crispi guides in size 10.5. If I run bigger boots like my pacs I move to kenetreks for the size. Rhe fl gaiters are nice to not have to mess with the strap and I have nearly worn through the material and still no failures. My kenetrek gaiters broke both snaps the very first time I wore them.
I can’t speak for the sitka gaiters but my first lite gaiters are one of my favorite pieces of gear. I’m 6’2 and wear a size 12 and they fit great but I don’t have the biggest legs either so I could see where if you have big calves they might be tight.