VR Appropriate Effects

Motion blur: Don't do it! Low-persistence is an important feature for a reason. Unless you want to make the user feel drunk, don't even consider motion blur.

I agree it is a bad idea, but how much of a bad idea? I am curious if low-persistence motion blur just looks the same as full-persistence.

Depth of Field: As you said: Don't do it. This is annoying and may really break the experience as it becomes obvious that your eye focus is off. (The focus is wrong anyway as you always focus on infinity in the Rift, but usually your brain does not mind that too much).

Perhaps a more half-arsed depth of field that just blurs distant objects would work. More of a simulation of atmospheric distortion to give you a depth cue.