I have the Adaptabell Max version. They are solid and the knurling is sufficient. My main gripe is that changing the weight is kind of a pain, so we don't do it. We ended up getting some powerblocks shortly after this so we don't use them much except for movements that are hindered by the powerblocks cage (overhead tricep extensions and the like).
I do think the upgrade to the Max version is not worth it. I would just stick with the plastic ones if I was to do this again.
Performance
Value
Build Quality