Your custom 212 cab might be in line with what I was hoping you'd do/what I've daydreamed about doing if I were an IR maker.
What I do like about Celestion IRs: The emphasis is on the speakers themselves, rather than the cabs. The cabs they use are a "neutral" basis for directly comparing different speaker IRs and how those speaker IRs in and of themselves are (dis)similar. What this also allows for is better/more natural mixing of 2+ different speaker IRs.
What I really like about OwnHammer IRs: I have found, and this might mainly be my neurosis, that when mixing IRs from different cabs, there is just something "off" or "unnatural" about it. I always prefer mixing IRs taken from the same cab. OwnHammer offers several multi-speaker packs which are great for these blends. The "space", "depth", "dimension", "insert adjectives here" just always feels more authentic. 75% of the time, I like using CabLab to blend 2+ speakers together, or just use two different speakers in the cab block. 2+ speakers sounds more "interesting" to me. I'll gladly take a G12H-30+G12M-25 over a G12M-25 any (well, most) days.
If I were a super rad and talented IR maker, here is what I would do:
1) Cab Series:
-Classic speakers paired up with classic cabs (aka what York is currently doing).
-This puts the emphasis on the cabs over the speakers. Or more correctly, the interplay of specific cabs and specific speakers.
-The Cab Series is for the purist/traditionalist.
2) Speaker Series:
-Get 3x custom built cabinets:
--1x 1x12" & 1x 2x12":
---1) with convertible back panel for open/closed configurations,
---2) with 2-4x removable grill cloths to a) pair right style grill cloth for right speakers (Jen P12 with Fender black/silver, or EVM-12L with Mesa cane weave), and b) to demonstrate the minor but noticeable affect that grill cloth material has on tone (see OwnHammer 412 ZLCS V30 MMMC)
---3) rear loaded and front loaded speaker mounts
--1x 4x12" with 2) & 3) from above.
-The Speaker Series is for the experimentalist (but traditionalist are welcome too!)
With the Speaker Series, you could sell separate packs for say a low gain speaker like Jen P12 in a 1x12+2x12 pack (open or closed, various grill cloths or no grill cloth options,) or a higher gain speaker like a V30 as a 2x12+4x12 pack. Or sell them as individual 1x12, 2x12, or 4x12 packs, or all 3 cabinets combined (see Celestion). The main attraction of this capturing methodology & sales structure, for me, is the ability to mix different speaker IRs, that are from the same cabinet, and not experience any off the "off" or "unnatural" funkiness I described above.
Please feel free to steal or expand upon or disregard my ideas. If utilized, Ill gladly take payment in future IRs. That's like Bitcoin for guitards, right?!