I think the NT -- well, later Windows in general, I guess -- version is the one that kept going until 2018. I'd always heard good things about it, but was over on the Mac side of the world with PageMaker and later InDesign. (While I'm still over in Macworld, when I need to do DTP-ish things these days, they tend to be in LaTeX, so I never actually looked up iCalamus, although I feel like I should give it a test drive sometime.)
It well might have been. I was beta-testing it the North American publisher (and got it for free, although they made quite a bit off me on Calamus SL and plugins for Atari TT030 I had before), even for a while after they sold to... Roxio was it? I can't even recall by now, but development was done in Europe.
They did some really nice things with virtual objects, being able to zoom in down to a printer dot, stochastic rasterization and all that.
There were some other very high-end packages for Atari as well --Didot, Retouche Pro, TMS Cranach. For some reason European developers really went wild developing professional-level DTP software for Atari with some very impressive results. Too bad Tramiels didn't do much to support them...
