I want 2 lenses in my arsenal a great zoom and a great prime.
I have a great zoom and now if like to get a great prime, and I love the 50mm f range. I own the 50 1.4 and it's ok but...
It's rather expensive and while I do have the means I'm kind is in the middle.
Sigh; yes. Which I do.
The fact still remains that the lens is weather sealed. The cheaper f/1.4 and f/1.8 are not.
"... you going to be shooting a lot of low,dim, scenes? If so the 1.2 will be justified."
If low light is your problem the difference between f1.4 and f1.2 is not a justifiable fact. One half stop in a low light environment isn't a deal breaker or maker.
"Buy a good tripod
This far better advise for low light.