Hourences, it is not as bad as you make it sound like when you get used to it and when you got a properly customized version of Max. It's not like that we are running on vanilla Max. Your "30 unnatural export settings" equals to zero with our setup. Yep, that's right there are absolutely zero things you need to set or adjust in max when you want to export it which is done in a matter of seconds after having pushed 1 button.
I have also done large outdoor terrains and it was for sure 10 times easier to do in Max compared to Source. We got preview of everything from lighting to alpha layers to scatter in max. The terrain creation process itself is easier in max and regarding exporting and previewing it goes a million times faster than in Source.