In reply to Offwidth:
Sure, I wasn't disagreeing with you, just adding a different slant.
As you say, it's a big job trying to make things consistent. But if a 6A in Yorkshire feels harder than a 6A in Wales, I'm not sure it matters that much as long as they aren't miles out. I think the main thing is that within an area, and certainly within a crag, the grades make sense relative to each other. That's what I've aimed for with the Lancs bouldering guide anyway.
Of course, there are really only two categories. There are crap problems and then there are problems you can do.