If you can break clay birds on a skeet range with #10, I bet you can kill woodcock with it. Like KWill, I am curious about RST's new woodcock spreader #10 load and I bought a box to try this fall. When I started hunting woodcock a long time ago, I used skeet loads (#9s), but I haven't seen much around recently and have been using #8s, or 7 1/2s, if I'm in an area when bigger birds are in season in the same area as woodcock.
I am going to order a box in 20ga, 16ga and 12ga just to have around. I am confident in my shooting that it is not the number of pellets per rounds but getting that pattern down to the target. I still like to try new items.