I'm looking at early feedback from this first week, and there are some trends emerging. While the base, numpad, and bars are all popular, the novelties are proving
very popular - enough that I think it's worth turning the Extension/Novelty kit into a pure novelty kit, that has a better chance of selling out completely.
To do this, some of the extension keys can be moved to the base, while others will need to be dropped.
Going by people's answers to what coverage is most critical to them, the UK keys can be dropped - not a single respondent has said they need those. Stepped Control, R3/R4 Page Up/Down, and 2u Shift should make the jump to base, as a decent number of people have said those are necessary. HHKB bottom row mods can be dropped due to lack of demand, although I'll keep the 6u bar in the bars kit, and there are 1.5u and 1u R3 novelties.
Interest in the alert row kit is lagging far behind all the others, and it would be dropped. While potential cadet alphas have gotten some feedback support, none of the proposed additional kits has enough support to warrant adding them.
A dedicated novelties kit can have a few more keys in it since the extension keys would be stripped out. I added 108-key coverage, and more row variants of the 1u novelties. You could physically cover XT columns with novelties, although I know that's not perfect.
The resulting revised kitting would look something like this. The 1.75u Enter and 1u Backspace for extended 40s support in the base could be dropped if needed to help with pricing, but the base is on par with most SA bases of the last six years.
Proposed base:

Proposed numpad:

Proposed spacebars:

Proposed novelties/accents:

I'm trying to keep the kit count as minimal as possible for the sake of vendors not being stuck with dead stock, so I don't envision being able to add any further kits to this. Part of me wonders if the numpad and/or bars interest merits merging them into the base to prevent orphaning, while the novelties seem so popular that I don't see them lingering on shelves.