Thanks Mike. I'm still struggling with getting mine setup correctly to zero to the bed, but I understand the virtues of it. I've built a similar fixed zero plate block at 35,-1.25 that gets surfaced with my spoilboard (remove the plate before hand). Here's a pic.
Next time, after this spoilboard is finished, I'll mount the plate permanently in an off-table block below the spoilboard & use an offset in the file so that I don't have to surface this block each time I surface the spoilboard.