Yeah, so I hacked the Sega Saturn Bios and removed regional lockout and CD authenticity checks. Obviously, that was the reason I was dying to get a Saturn a couple of days earlier. Thanks to an unnamed individual, I've got one now and promptly installed that modified Bios.
Good news first: regional lockout bypass works just fine on real hardware.
Install this Bios in your Saturn and play any authentic game in any video mode you like, no need for clunky switches or cartridges anymore.
The bad news: Although the CD authenticity checks in the Bios have been removed, CD-R copies still don't boot.
I basically have zero debugging capabilities on real hardware, so I can't really tell what the exact problem is, but credible sources suggest that the CD interface has to be unlocked by initializing with a genuine Saturn disc before being able to boot a game disc. This is rather unsatisfying, but I'm releasing this anyway, it's better than nothing.
I'll be getting a modchip for now and will have a look at this again once Dr. Decapitator has dumped the CD interface program ROM.
I could imagine that there's a debug command hidden somewhere that lets you boot CD-Rs without authenticating first. We'll see...
Also, if you plan on installing this Bios in your Saturn, keep in mind that the pinout of the original Bios maskROM is similar to the 27c800 and don't forget to byteswap the ROM before copying it to a 16bit Eprom. Btw, this hack is based on the japanese 1.01 Bios.