Only you can decide. Some examples from 70-200 2.8 IS Lens using autofocus, f7.1, 200MM, handheld, 100sec. It was only painful when I wrote the check, but now the pain is gone and it didn't even leave a scar!
Finished product
Cropped from above pic with No Photoshop
Eyes Sharpned amount 99% .6 radius 1 threshold
Ken