Shooting at 1.4 is tricky stuff and rarely needed. I am often an "available darkness" shooter, and until 3-5 days from now (Hurry UPS! Hurry!), shot/shoot mostly on a Nikon ft2 with a 50mm 1.4.
And let me tell ya, 1.4 is NOT FUN!
You can pull it off, and sometimes you need it, but the DOF is VERY shallow and usually your shutter speed is very slow, so THAT opens up a can of very blurry worms. As in "opps the subject moved 6 inches after I focused and is now out of focus" or "opps I moved too much and the whole thing is shot to hell."
Honestly, I am VERY comfortable at 2.8. I WILL use 1.4, but 2.8 on a 50mm is pretty sweet.
This shot for example was done at 2.8. It would look like hell at 1.4.
At 1.4 I would be loosing so much DOF at that focus that it would really detract from the image (at least in my opinion). Plus, getting that DOF placed "just right" would be a lot harder.