Ive yet to dig deep into their gear yet, but I can say that One of the first things that jumped out at me, is that Overstayer has included a parallel mix function. I used to use parallel processing all the time; back in the days of desks, I'd use an sux send (as opposed to inserting directly on the track I wanted to process), and I would send the aux out to the input of an OB device, then return it to a channel input, where I could blend it in the mix.
Like you guys, I've used plenty of OB gear... 1176's, LA's, DBX, API, etc. And they were all great pieces...but I can't remember ONE outboard compressor that ever featured a parallel mix function. Certainly Verbs and Delays did, but not actual processing. Maybe there were a few pieces that did? But I can't personally recall any. Anyway, like I said, I haven't digged deep into this company yet...but the parallel mix adjust certainly caught my eye.
FWIW

parallel compression has become more in vogue in recent years. i think part of the reason is digitals dynamic range permits the recordist to capture with little concern for dynamic range.

24-bit modern HD formats have a dynamic range of over 144dB while 2" 16 track analog was perhaps 100dB at best (with DBX) and less with Dolby A and even less sans NR, so what the recordist was forced to deal with was reducing dynamic range at capture. analog tape has a compression effect as well. no matter how light or hard you hit it it's going to compress the signal just a little. back in the day, the goal was to get to 70dB of dynamic range for vinyl, radio and TeeVee. but now we can capture multiple tracks @ 144 dB and that can make for a hairy mess.

i haven't had the "library" time yet to read the article but i will keep an eye out for it.

Without having used it to really put it to my test, I like the idea of this and see it as something I would pass a 2 mix through on the way over to DAW 2, prior to mastering.
It reminds me of the old Sonic Maximizers, this time its a compressor harmonic maximizer.

Generally MIX speaking: I have zero interest in mono OTB mix processing. However, high quality stereo 2 bus stuff is always cool to me.

it's obviously intended for 2 buss.

IMHO, on the topic of improving the 2 mix, a Bricasti is far more useful on a 2 bus though.
Rather than the process holding down dynamics, or artificially augmenting specific freqs like this appears to do, the Bricasti simply (brilliantly) just opens up whats there to begin with, thus... lets the sun shine in rather than cloud cover with electrical spikes called harmonic enhancements. I think our DAW software does all this stuff better.

Bricasti's are expensive but other than adding a tube or tranny pass to simply colour over a mix (like adding silk over HD TV), a Bricasti reverb is really about the only OTB tool I see me ever owning again. ITB 2 bus processing is hard to beat. Some day computers will be powerful enough where one Bricasti will fit but as of now, they take up the entire box just to run one unit.

Being said, I'd love to try this :)