Inkscape is much more as Illustrator
Blender is more close to C4D, or Maya
Yes both run well togheter but you can't expect the same level of integration as between PS and Illustrator
This DVD
viewtopic.php?f=12&t=1224&p=13989#p13989 is full of pratical examples and tutorial of integrated workflow between Gimp, Blender and Mypaint
Anyway MAC users are not much lucky even with multiplatform SW:
usually are not the main delelopers but advanced users to take care of the MAC , Win and Linux version
but Mac users seems not very active ...
So for sure there is Gimp for Mac ,and i suppose also Inkscape and Blender but maybe with much less add on and plugin available...and often there is bigger delay in the release of the last version
And maybe there is not yet a Mac version of programs as MyPaint and Alkemy
But if you used Photoshop on Mac you should have already noticed: most of the third party PS plugins can not work on Mac
I know was a mith about MAC be better for designer but if that mith had some true, that was many years ago
PS i see only now Rod reply
I never used Scribus so i can't comment but i found Inkscape quite close to Illustrator ..well less powerful...but as for car much depend on the driver