K's arcade listing indicates it works for all Whitestar, PinballLife says just the modified Stern Whitestar... both are listed as 520-5300-00. Need to figure out who's right.

Seems 520-5300-00 is the modified Stern version w Atmel, 520-5136-16 is the original. So does the Stern one not work for Segas / original Whitestars? Or what are you referring to by "early version boards"?

I see what you mean, I've also come across different answers doing some research. But I did find one official-sounding statement, which sounds good to me.

Games that are only compatible with the BSMT2000 chipset are Roller Coaster Tycoon, South Park, South Park Profanity, Space Jam and Starship Troopers. For all other games you can use the new 520-5300-00 White Star (Atmel) CPU.

Although not what we're talking about here, going the other way, substituting the original board into a machine that has the Stern Atmel version, may or may not work. It sounds like at some point Stern extended the emulation beyond what the BSMT2000 does or at least requires more memory.

Yes, it does actually work in some instances. In fact, Stern themselves used both versions of the board in T3. Your experience isn't representative of all machines, just as T3 isn't. So as I said, it may or may not work.

Wow, just bought one on PinballLife ($439), but you're right, don't see them now. Sold out already?

No reason to use batteries on this board, NVRAM is as simple as popping in a $3 chip. If you can pull a chip, you can upgrade to NVRAM on this board.