Mike may have is own justification for that, but here is mine. I did a stress analyisis on some Jesel rockers for an engineering class years ago in college so I'm not pulling this out of my butt. There isn't a substantial twist problem with the rocker offset that much. When they get offset enough so that there is no overlap between the pushrod end and the valve end of the rocker then you get close to seeing some twist, but if the section between is suffeciently large it's not a problem.
The problem is side loading of the pushrod side of the rocker due to the pushrod angle. It does two things:
1. It puts a lever load sideways on the pushrod end of the rocker arm. Looking at my s2 rockers, they are as thick side to side than they are up and down in the high stress area, so technically it should still be safe. But, you when you start side loading the adjuster screw, it may be questionable. Making sure the pushrod adjuster is up inside the body of the rocker will greatly reduce the potential for failure. You really want to be sure that there is enough ball on the pushrod so that the straight/tapered side of the pushrod doesn't bind on the edge of the adjuster.
2. The other problem is the thrust load between the rockers, and from the rockers to the stand. There won't be anything to break there, but wear will go up. Mike, you may already have a solution for this, but if not. If you added forced lubrication there and/or up the surface area of the bronze spacers it should help a lot. If you add the rocker arm pressure lube port to these heads similar to the stage heads, you could drill the shaft a under the spacer bushing and lube these points pretty easily. I don't know what kind of hold down that is on the end of the shaft, but I would definetely run something like that in all positions so that you have 360 degrees of area to support the side load from the rockers. I would be glad to help with any engineering you need if you want.
