I only own an 0561, but I've handled all three. I have nothing bad to say about my 561. Steel is great, flips like nobody's business, is surprisingly light in hand, has zero blade play, and has great ergos. The jimping on mine is not overly sharp, and I've had no issues with grit getting into the pivot - but then I haven't used it at all outdoors. It's easily my favorite flipper, and my second favorite knife overall (second only to the Umnumzaan). It is quite large area-wise in the pocket, but is not overly thick. I dedicate a pocket to my knives, so this issue doesn't bother me. The new model also has a steel lockbar insert (mine does not), which means lock wear is pretty much a non-issue.
The Adamas is almost stupidly overbuilt, to a degree that's hard to judge in pictures and video. In my brief time handling it, it seemed as though the handle was twice as thick as my 0561 (that's probably not true, but it sure felt like it). Felt like an absolute brick in hand, and in the pocket. The handle was so thick it felt like it was going to run into things while it was in my pocket. It certainly seems solid as all hell, but was just too heavy and thick for my tastes (and I like big heavy knives for the most part). It's a shame, I really wanted to like it and I love how it looks.
The Sere 2000 I was not impressed with. It seemed heavier than necessary for the blade size, and the one I handled had substantial horizontal blade play. This could have simply been a lemon, but it bothered me. Plus, it's over $200 for VG-10 steel. I'm not a steel snob, but if I'm paying that much money for a knife I want to see a premium steel.