I will write it it notes if you don't mind :- ) It's quicker and I will be less confusing.
1) For workstation system drive, randomized performance (reading/writting) is
all that matters. In this regard, I've seen quite different benchmark results, that go from none advantage, to modest advantage. But the more positive ones, show the randomized writting is about the same, but reading can be up to 50perc. better...that's already quite much.
2)950 PRO is both and MLC and 3D Vnand drive. This is something that should provide potentially better longevity to drive, something that is plus on system drive. On other hand, I haven't seen a single issue with 850 EVO, current SSD drives are almost immortal. All of the good ones.
3) 3dsMax opening would be negligible. Reading of 1GB file would take 1.5 second, instead of 2 seconds. But when was the last time it opened so fast ? It didn't, because most of the opening time is on software level. Your Photoshop file openings would get faster.

Generally if you feel like the additional money isn't too much for you, then I guess you should go for 950Pro. If you're budget conscious, then I don't believe the nvme drives are benefitial for system drives for anyone who doesn't constantly transfer huge data loads sequentially (people who work with video transcoding,etc..).