Dude, my bad. I just pulled out my expeditions, and you're right. The Cordura goes up the entire inside leg...Not sure why I thought it was just goretex up there. My mistake, sorry.
How bad are your snags? If they are just holes, you can put seam grip over them...it'll be waterproof. As a matter of fact, you probably could get away with just cutting out a panel of cordura, seam gripping the edges, and slapping that over the goretex panel. It'll probably reduce the breathability though. I find that shoe-goo works well too, having used it to repair torn CCF pads etc.
I only have the expeditions, but I use them for both my double plastic boots, and my single boots. I have a size large b/c of my foot size (9.5-10) not because of my build. I'm skinny like you at 5'9" ~143lbs, and the gaiters fit okay around my calves. I have skinny calves though, so they fit a lil loose but not unbearable. A lot also depends on what I'm wearing for pants. They def fit sloppier when i'm using them with my single layer boots, but I haven't had any issues with wetness and snow permeating through.
Also, be careful with your crampons... I can't say that I endorse running with them. Many injuries and broken legs every year b/c of improper use. Sometimes it's b/c their points get caught on something, but their body wants to keep moving. Other times, the points get caught when they are trying to self arrest (remember to bend those knees!), and it actually flips them. Think body over bike handle bars b/c you slammed the front brake. Be careful out there!