I think the 40s support could still use some help. Notable missing keys include a 1u R2 Esc, a 1u R2 Tab, a 1u R4 Raise and Lower keys, and 1-2 1u R3 Shift keys.
I think you would be okay to remove one or both 3u spacebars. I also think that the 1u R1 Backspace key would fit better in base. Also, does there need to be an alpha-colored 6u spacebar in there, or is the pink 6u bar in the sakura kit good enough?
I would definitely prefer that the addition kit be changed to a 40s kit, and the actual addition keys be moved into base (assuming they don't affect base price all that much). However, I'm definitely biased here as a 40s user, and I would love to hear the opinion of those that are interested in the bob-40s keys in the addition kit.