If it means enough to you, and you have a desired to see it slabbed, I'd submit it.
Who cares about the Green Label stigma if you know personally these were really signed by DS? And I bet if those books came up for sale on the market, others would care less too.
I probably will send a couple for grading, I just haven't decided how many yet. I've been going to conventions for probably nearly 20 years and I have a long box full of autographs (I should have been getting sketches in the early days instead ) I have the same issue with so many of the other books I have because I really want to preserve them for the long haul.
It might be a few months but I'll post pics of hopefully quite a few Dave Stevens CGC slabs in 2011.