it has gotten bad, not just for users of your magnitude, but even for us minnow's. Every post gets a spam, you can usually spot the in two ways, they will be close to being first and they usually will not upvote your post. I like your idea on 1 full upvote per post for the best and most relevant. But what happen if that comment comes in 8 hours after the post. Alot of people upvote the first few comments that come in. Maybe they dont read anymore comments after that, and maybe, just maybe that comment gets made on day 5 or 6 of the post, then you have an excellant comment going unnoticed. Sorry just thinking out loud here. I am sure you get where I am going. Awesome post and thanks for bring the much needed attention to the matter.
I pick some later comments too, but like to have one on display early. It's okay to think out loud.