Please add R3
Pg Up, R4
Pg Dn to the base kit, for 65% and 75% users. (The actual reason is that I wanna have an excuse to buy this set.)
Also, please change the R4 1.25u
Menu legend to
Fn (alternatively:
Meta,
Code — just as long as it's not Menu, as that's the least versatile legend).
I think including another R4 1u key with a different legend would also be worthwhile (e.g.
Meta, like in
GMK Muted 2 and
EPBT Be The One). This helps cover some oddball 60%/65%/... layouts. In fact, since you already have a 2u Shift, it would make sense to also include this key.
Finally, you may want to consider adding 2× 1.5u
Super and a second 1u
Alt key, for Mac and OG HHKB bottom row users, as well as a R1 1u
= numpad key. However, these suggestions are lower priority than the ones listed above.