Have any of you used this? Is it feasible to hand-hold?

I was wondering the same thing. I'm not savvy on OM-D, just know about the in-body stabilization. I assume there would be no way to get autofocus using an EF lens?

That's true... also no way to change the aperture with the camera; you use it wide open. (It's possible to close it down on a Canon camera and remove it without powering off, then mount it on the OM-D; but I can't imagine wanting to do that with this lens.)

Mine is sharp wide open, you should be able to use it that way till you max out your shutter speed, or need more DOF.
If I remember right it's very near identical to the FD version.

IBIS works well at that focal length. 2-3 stops easy. I get 2 stops with a 600mm lens.

Ernie Aubert wrote:
That's true... also no way to change the aperture with the camera; you use it wide open. (It's possible to close it down on a Canon camera and remove it without powering off, then mount it on the OM-D; but I can't imagine wanting to do that with this lens.)

Agreed on the aperture, I almost always shoot the 400 at 5.6.

It's perfectly fine to handhold on a Canon body without any IS so should not be a problem with the IBIS on the OM-D. As mentioned, tack sharp wide open.

Ernie Aubert wrote:
That's true... also no way to change the aperture with the camera; you use it wide open. (It's possible to close it down on a Canon camera and remove it without powering off, then mount it on the OM-D; but I can't imagine wanting to do that with this lens.)

With a Redrock Micro EOS-u4/3 adapter, you can control the aperture. It is not very practical in use because of the external 9V battery compartment. However, when you set the aperture and turn the adapter off, the aperture does't open up. That way it is possible to set the aperture for use on any physically compatible camera without removing the lens from a Canon camera with power on.

With respect to image quality and effective reach per weight and cost, the lens / camera combination is an excellent choice.