Thanks for the info, Dave.
I might look into getting a Boyd's. I probably won't be getting a Monte Carlo, however. I just put my 870 in my shoulder, and the SPS barrels sights line up perfectly with the OEM stock and a neoprene sidesaddle. Any higher and it wouldn't be perfect.
If I ever get one of those Mesa Tactical AR kits and put optics on it, things might change, but the more I read about it, and the more I handle mine, the more I realize I want to save the mall-ninja stuff for a fun "project" gun, and not the HD one.
A PG/stock or thumbhole would be easier on the wrist, though.