pc crashed while writing original reply, so just going to speedrun this one-
Thanks for the info, it's possible to change the base piece to have two sets of mounting points - both for Pro 1 and Pro 2. I think the trade off might not be worth it though, I doubt people would choose a Pro 1 over a Pro 2 to donate parts for Evija.
I opened up my Classic today and it's very different to Pro 2. It'd be possible to have both work in one design, but like the Pro 1 vs Pro 2, the Pro 2 would be the more likely donor due to price and the additional functionality it offers.
so i watched the evija assembly video and noticed that the plate had a cut-out for a capacitor on the main pcb, and it reminded me that the components on the main pcb of the pro 1 are different than the pro 2 as well (both on the bottom and top of pcb, with the notable "big green chip" on top of the pro1). so there may be further compatibility issues with the bottom of the case, as well as with the plate, making it even less worth your while (and likely more expensive) to offer a pro 1-compatible evija.
in terms of offering the classic-compatible evija, it's just one of those things where offering it means you can future proof the case so it doesn't turn into a 356CL situation ($10 ps2 to usb adapter attached to $10,000 keyboard). usb-c has a lot of potential, and so we might be seeing custom classic controllers that offer things like internal full bandwidth m2 ports, or maybe even the ability to turn your keyboard into a mobile battery pack that can fast charge devices on the go, and that could give more reason to want a classic pcb + custom classic daughterboard in an evija case. i don't think there's anything holding anyone back from offering the same level of type-c compatibility with a custom pro 2 daughterboard though (just the general cost/availability/licensing for things like tb controllers, and the obvious lack of usb-c cutout on pro 2 case), so might be that it gets the engineering love and not the classic.
downside is that the classic supposedly has qc issues, so who knows how long this iteration will last. i also feel like the faraday60 has more potential than the classic (and i believe it's being designed with the pro2 case in mind, so it'd likely work with the current evija), so it may become a big player in the custom topre hhkb space.
obviously you could just wait and see how things with the classic play out though, and then maybe do a run for it specifically down the road so that you aren't effectively wasting production time on it now (i'm of the mind that if the ****ty red massdrop brick could get more than 40 backers 4 years ago, your 40-case drop is going to be devoured in 2020).
I had a few people request a typing test on a deskmat, as that's how most people will use it - take a listen 
definitely a crisper sound, but i personally can't stand the stock hhkb sound, so hopefully you/one of the HG owners are able to get us a proper type-s typing video at some point
you did miss out on an easy opportunity to compare the evija sound with the plastic hhkb sitting directly above it though
here's one more question on sound (and it's one of those things where once you hear it, you can't unhear it, so i'll spoiler to keep you from reading something you might not want to be aware of if you're noise-conscious)-
so each key press has its own sound profile on the hhkb (and unfortunately a very silenced board isn't immune to this problem either), and my guess how the profile is determined is that the closer to the edge the key, the "worse" the key sounds (making the esc and backspace keys the worst-sounding 1u keys by far). with the change in case material and mounting method, maybe that changes though, so i'm curious to hear if you're able to notice a difference in sound when typing on the 'a' key compared to the 'g' key.
i assume this affects all keyboards (seems like an acoustic property thing), but i haven't really owned any board other than a hhkb in 5+ years, so i figured i'd ask.
