Not sure why that would be necessary, but I would like to hear from someone that has done it.
Benefits;
Easier to set up, by miles. Including getting piston pockets and clearances more accurate.
Lighter , so better valve control at high revs
Less oil useage, so more for bearings
Less oil in the head, so less slosh/aeration potential
Better valve control due to no compressability
Downsides;
Maintenance every once in a while. Surely not an issue for race engine
Time consuming to do 1st time
Cost of materials
Anybody?
Jon