If I remember correctly, they're more "traditional" network devices, in that they're mostly concerned with doing packet-level stuff and doing it well. I'd love to get a FastPath, maybe one day I'll find one . It'd be interesting to see whether there's a performance differential brought on by the GatorBox's "do everything" approach.
Yeah it's kind of a tricky subject, at least as far as use in Macs goes: sometimes they may be pin and signal compatible but ROMs don't recognize the new chips so they won't work. Upgrade suppliers such as Sonnet, Newer, and Daystar had custom firmware updates for some models that used new chips, such as the 7448 upgrades for late-model PowerBook G4s and G4 upgrades for B&W G3s (though these models supposedly worked with G4s until Apple blocked them with an "update", thus requiring a 3rd party firmware patch to reenable the use of a G4).
Chips that are supposedly pin-compatible:
QFP 240: PowerPC 603, 603e
CBGA 255: PowerPC 603e(v), 604(e)(v), 740
CBGA 360: PowerPC 750(L), 7400, 7410
CBGA 292: PowerPC 750FX, GX
CBGA 483: PowerPC 7450, 7455, 7457
CBGA 360: PowerPC 7440, 7445, 7447(a)(b), 7448 [though it's still a CBGA 360, it's not compatible with the earlier CBGA 360 used by the 750/7400]
Maybe one or two of the PowerPC 970 variants are pin-compatible but they're epoxy-sealed to their carrier boards so they're very difficult to rework. Not that there would be much reason to do it anyway.
The PowerPC 750CX has a unique BGA.
Though they use the same 304-pin QFP package, the PowerPC 601 is not pin-compatible with the 601v, nor with the QFP variant of the PowerPC 604.
JLCPCB now has the order, estimating 1 week til delivery - I have 2 boards out of that batch to spare, so - who here has an SE with battery damage, or one they can pull the customs out of, to test this recreation?