Hello,
actually there is no formal integration between Cubase and Dorico (although that is a common dream of many) but you can export midi or audio from Dorico and work with it later in Cubase. I don’t normally use the score editor in Cubase (a couple of times I have), but until I understand it is powerful, not being so great as Dorico, of course.
And regarding opinions on Cubase, well, here are we at the Cubase subforum, so I guess opinions will be in general positive. For my side I can tell you I wouldn’t switch to another system even if someone would pay me very well. I speak for the Pro version. I can’t say if the newer versions will run in your old Apple, but at least my Pro version 11 runs very well in an eight to nine years old notebook with i7 processor, 32 GB RAM. With less RAM should be run too.