The 40s kit should have the spacebars that are most common 40s layouts, namely 2x 2u, 2x 1.5u, 2x 2u, 1x 2.25u, and 1x 2.75u (I may be missing something). The spacebars kit should come with the weird spacebars, and potentially include a duplicate 6.25u and 7u spacebar so that 40s that do use those spacebars don't have to buy a modifiers kit to cover it.
You're missing 6.25u and, potentially, 1.75u. However, I think that
6.25u should be included in alphas anyway and not mods, because it's used on most/all sizes that this set aims to cover.
Second 2u may or may not be worth including. There is a 2u space in the spacebars kit which can be used for this, like there is a 2.25u key which can be used for 40% boards that use 2× 2.25u.
7u space is not used commonly enough to justify including it; I think it should stay only in the mods kits. It falls into the category of keys such as R3 (KAT R2) 1.5u Tab, used on 40% boards such as Romeo and Equinox. Those boards were designed to be covered by standard base kits, so they don't make a good basis for including such keys in 40s kits.
And all the Alice an split-keyboard users?
A copy of 2.75u, 2.25u, 2u, 1.25u and 1u spacekeys should definitely be included in the spacebar kit as well, imo. This benefits both ≥60% boards (Alice, split space) and 40s boards (double 2u, double 2.25u).
