I just placed an order for those 18\" sportsmans guide snake boots myself.
They have several qualities that are better than my old heavy boots.
The older I get (49 now) the more I can appreciate equipment that makes those long days tromping the hillsides go a bit easer on me.
These new boots are nearly 2 lbs lighter than my old ones and 2\" taller - no doubt the weight reduction is going to help me out some.
Don't get me wrong now - I can walk the hillsided plenty good - I broke in a nephew a couple years ago - he was in his late 20's and wanted to learn how to find seng. I took him and trained him and after about 4 hours on that first days hunt he was laying down and about to pass out and I was still going strong. After two or three more hunts he got used to it and was able to keep up well enough.
On the Snakes up-hill hitting you above the knee. I am sure that is possible. But in those 2 years that I worked for the timber company (in some seriously snake infested areas) which are very hilly almost all of the snake bite attempts were in the ankle or lower calf area and the only snake bite that actually got thru was very low on the boot (just behind where the little toe connects to the foot). The leggins we wore did not protect that area - they mostly protected from the low ankle area up to about knee height.
We got several hits on the leggings on a weekly basis. You could hear the pop when a copperhead or rattlesnake tried to bite and hit that hard plastic leggin.
We worked as a team of about 25 guys, with hatchets cutting a ring around trees, and then another group squirted a chemical into the cuts and that killed the trees that were left.
When you have 25 guys lined up tromping thru the woods whacking trees with hatchets, you find just about every snake in the woods and even worse (to me) was all the yellow jacket's and hornets we stirred up.