When I read these sort of statements I wonder what I am doing different from other people or what they are doing wrong because I experience none of those symptoms on my MX Blacks. For me, the strong force at the bottom but relatively light at the top makes it so that bottoming out is softened or...
Game runs smooth as I can hope for on my 6950. Occasional drops to ~45 fps when looking at a city from a distance or something but that is about it.
I also haven't experience any mouse lag or anything like that either.
I definitely do this too. I never pick up anything unless it's a 10:1 money/weight and even then I end up dropping a lot of stuff for better items.
But I have a bad habit of forgetting to sell stuff and end up dropping some valuable stuff.
I have only had one crash at one point when I entered a building. No errors or anything just dumped to the desktop. Aside from that everything has been butter.