I'm wondering if the Lite-on iHAS CD/DVD drives would be a good starting point for my reverse-engineering efforts. Without Blu-ray support, maybe there's a chance it'll be less obfuscated and better documented.

I know that Team Xecutor was able to get them to extend the capacity of DVD+R DL discs with the Burner MAX payload, but it's unlikely I'll find any public information about how they did that.

Maybe I should start by digging one up and seeing if I can get a firmware dump.
In particular, I honestly find it incredible how Rib got the MT1959 drives to read Xbox/360 discs and make it seem so effortless.

There hasn't been a computer disc drive that has been able to easily read these discs since a few select Samsung/Toshiba drives and Kreon firmware, but also, the Kreon firmware never got updated to support dumping of XGD3 discs.

I feel like if the multi-session fucky-ness of the Xbox Game Disc 1/2/3 format is do-able with Omnidrive, I feel like it
should be possible to get a drive to at least seek to the high density area of a GD-ROM, though I imagine the track being high density could be troublesome for the drive's chipset to interpret.

At least XGDs are much closer to plain DVDs than GD-ROMs are to plain CDs, from my understanding.
Though I'd have to move a bunch of stuff to get to my many, many DVD drives, which are currently lining the bottom of my plastic shelving in the closet, to prevent the shelves leaning from all the stuff stored on them.
There's gotta be at least forty of them. I just kept collecting from recycled and decommissioned machines in case one model or another became useful for dumping specialized discs.

Besides, I think it's good to have a bunch of different models of drive for troublesome discs. I've had some that throw a bunch of errors in one drive while working just fine in another.

Zero (working) Plextor drives though. :c