I was at my nephews graduation and I pulled out my 50 to have fun with it. well hope you dont mind the noise, I didnt want to use my flash to much but i like these shots
D700
85mm 1.8 D
24-70 2.8 ED
70-200 2.8 ED VRII
2xSB900
Elinchrom Ranger RX 1100watt heads.
I don't see any noise on these. In fact I don't see any on my D300 up to 3200. These pictures look sharp enough but 3200 ISO would have allowed you to use 1/60s which is a safer bet with a short tele like the 50mm.
Otherwise - yes I see the usefulness of the 50mm f1.8. Though I tend to hop from the 35mm f1.8 to the 85mm f1.8
Charles
Nikon D800, D7200, Sony RX100m3
Not buying any more gear this year. I hope