Yes the 210mm has been discontinued due to low demand, but I think Linhof Studio has one left... so if you're faster than me to get it you can have it. Linhof Studio show which lenses that are discontinued in their list on the web, but it's often possible to get the discontinued ones still.
I have myself the 180mm which I'm pleased with. An advantage over the 210 is that it's smaller and lighter, and it can do f/5.6 with copal 0 (the 210 requires copal 1). I've been thinking to get the 210 too, but it's so close to the 180 so it's more likely that if I get one more it's one of the legacy analog tele lenses, say 240 or so, but those do have sharpness issues (a kind user provided me with test images with various 4x5" analog teles on a P65+ back), but still beats cropping.
In practical use I've noted that it's often hard to get sharp results with the 180, not due to the lens, but due to the narrow angle of view, so if you shoot landscape on a distance you often get issues with atmospheric distortion. There's also often problems with depth of field for such narrow angle of view compositions.
On the Linhof Techno the stability of the rail is also challenged, so one need to be extra careful when pressing the shutter to not introduce vibration, but I guess with the Cambo pancake that won't be an issue. You'll have to carry the weight and bulk of the tube though.
Concerning sharpness I have not really seen any comparisons so I don't know. I'd expect a lens this long to be quite sharp on any system, and as said I have no complaints on the 180 but then I have only a 33 megapixel back. A comparison would be interesting to see, but long lenses are rare so I haven't seen a single test. One cannot expect the same "tech cam advantage" as on a wide angle lens though, so the Hasselblad and Phase One lenses probably compete well with these.
Both the 180 and the 210 are tele designs (ie not normal lenses) which means that performance is probably not as good as your 120, one could look at data sheets to get a clue. The sheets are hard to get now those since the links on the web is broken, so I haven't seen them myself. If someone finds links to these data sheets please provide a link...