To be honest TS, I feel whipping out extra $1700 for a lens that has only 1/3 more stop very expensive.
However I must also confess that the 50mm f1.4 is a problematic lens. The USM motor runs on a gear chain and it will be easy to worn it out within 2-4 years of usage. It cost 25% of the lens price to get it replace.
For performance wise, the 50mm f1.4 lens is averagely usable at f1.4, when you nail the focus and its mostly luck than skill (coming from my experience) The bokeh is rather neutral at f1.4.
Like you I struggle about 14 months deciding to buy the 50mm f1.2, asked many professionals in the wedding business and it was only after my 2nd copy of the 50mm f1.4 broke down the 3rd time I was without a 50mm workhorse for 2 months when I decided to purchase the f1.2
The f1.2 is very reliable, like the f1.2 of the 85mm lens. Its does not produce the swirly bokeh of the former, but its more pleasing to my eyes than the 50mm f1.4 at f1.4. As my usage increased, i find myself more and more whipping out my 50mm than before I had my 50mm f1.4.
As for price, take heart, the other L brand is retailing their 50mmASPH f1.4 at $4400 and 50mmASPH f0.95 at about $15,000. So if you afford it, i say go for it.