Like Dave Matthews, I have so much to say on this topic.
"How happy an opinion makes me feel comes dead last on my Validity Detector List. "
Ah, but the fact that it is on the list at all is extremely important. Why? Because, as an agnostic, you know that there are many things which we will never know, including the existence of God (whatever that is), the existence of "things in themselves" (or Ultimate Reality, or whatever), and the existence of "true" knowledge. Thus, everything else on your list is an unknown and you are left with aesthetics.
But then I must stop myself. There actually is something else on the list (probably before aesthetics). That is the effect your beliefs have on the world. However appealing it might be, Christianity (along with other religions) has indirectly been the result of much suffering. One should surely eliminate it just on this. But there is something else to take into account -- it might have improved a lot of people's lives as well. That is, it may have gone way beyond mere aesthetics. So which one is more significant? I have no idea. It's possible that we will never know, so this brings us back to the agnostic standpoint. Not only do we not know about God, but we really have no way of fully guaging his/her/its affect on people.
For me, this is all a moot point anyway. I am agnostic and I have many reasons for it, one of which is that I find it the most aesthetically pleasing. It pretty much leaves open an infinity of possibilities, something which is very appealing. Furthermore, it removes any bias towards a particular group of people by virtue of their beliefs. All religions and spiritual ideas are equivalent in the agnostic view, they are all possible and they are all unprovable. Also, it just makes more sense to me, particularly given my scientific training.
"if it could be scientifically proven, beyond a shred of doubt (let's say, with equal confidence that we say the world is round today) that God does not exist, would you want to know? If you came across this discovery yourself, would you release it to the world? "
I would definitely share it with the world. Hopefully it would shut the fanatics up and suddenly force people to open their minds to something else. Of course, you will always have your Ray Redbournes of the world, those who don't believe anything they don't want to believe.
"However, agnosticism is a perfectly fair compromise because we simply admit our lack of knowledge. For you to call that position deluded or dismal frustrates me to no extent. It sounds strongly like you would discard intellectual honesty in favor of a dose of morphine. "
Actually, it's probably more a matter of reveling in the illusionary importance of humans. Ego, that's what it's all about. People just can't get over the fact that they're not the center of the universe. I can't really say that I understand it (of course, I guess I have more outlets for my ego than some), but I really hate it. People really need to look more into the Copernican Principle.
"And by the way, I find the prospect of Hell to be far more terrifying than no God at all"
I agree. Maybe it's my American biases (we gotta have our freedom), but I find the idea of having a constant eye looking over my shoulder to be absolutely repulsive and totally senseless. I had little respect for this kind of attitude in adults when I was a child, so I have trouble picturing a deity in this manner. I suspect that it's a tool of control, both by the church (historically) and by parents. It works like a kind of dictatorship over thought. If you were a German during WWII, Hitler could control your body, but he couldn't control your mind. The church can do both. Which one is still around?
P.S. It occurs to me that Hitler did control their minds (with propaganda), but I think it was on a much shallower level.