Hi Craig,
You might use the low poly object in your scene and then cache the MoGraph set up. Then replace the “proxy”.
You mentioned out of focus, which might indicate that you like to have the objects in focus as hi-res and the blurry ones low res? This could be done with a Plain Effector, attached to the camera and with a fall-off enabled.
The Plain Effector is set to Modify Clones. I assume you get the idea already.
However, 3x3x3 means 27 times 980 polygons in your example, which seems not a lot. Please contact the Support, I’m not sure what could have been caused it. This needs to be cleared.
I’m not certain if X-Ref might be of help here, as I do not know your set up.
All the best
Sassi