Yes, but more isocurves on complex objects are confusing to me …
I would need to rise and then lower the isocurve number repeatedly for several objects … too complicated.
But I have to remember your suggestion about using shaded mode when needed.
In certain cases it can certainly help. 
Yes, unfortunately Rhino 3 was not able to keep Rhino 2’s smoothness …
For example, at times I have to split a large surface by many smaller (poly)surfaces.
And those splitting objects are already selected due to previous operations.
In this case running ‘SplitBack’ on the already selected splitting objects and simply select the object to split feels simple and fast.
Having to lose that selection to run Split, select the surface to split and finally reselect all those splitting objects (often a difficult/long task) … well, feels somewhat stupid. 
Thank you, Jim !
Regards