prodos disks mac <-> GS ?!

[Benjamin O Zotto <zotto@nospam.fas.harvard.edu>]

Hey all,
There have been a lot of posts/threads recently regarding the trickiness
of getting IIGS software to a IIGS via other systems, and in particular
via Macs.  It is unclear to me, however, exactly what the requirements
are.

I (for example) am trying to get apple's system disk 3.2 and/or a game
(in .SHK form) to a prodos disk from the net. I am a PC person, but I
have access to several different Macs.  Expanding the System disk via
DiskCopy onto an 800k floppy seems to work fine but produces an unreadble
disk to the IIGS.  I can format a floppy as Prodos on the Mac and then
manually drag the files (like the .shk) file onto it, but that either
hangs the Mac (!) entirely or produces a disk that is CAT-able on the
IIGS but which has Disk I/O problems (Prodos error $4B) when I try to
use any of the files.  The Macs are all *relatively* new (all powerpc's,
but not the newest ones).

People continually suggest using older macs, and Apple's TIL tells me
to use a drive that has electronic disk acceptance.  Can anyone pin down
exactly what the technical difference is with these drives or systems?
Why would certain ones work and not others, even though they *all* appear
to work OK just looking at the software? Why do some only "sort of"
work? It doesn't make sense to me that there isn't a cut-and-dried means
of determining compatibility.  I'm getting frustrated to where I'm tempted
to pick up some really old 68k Mac but I'm even then uncertain whether
I could get good results (and/or net access :)).

I guess my question is: what's the problem with the newer Mac drives?
Why are they so different, and in what way-- and what's a surefire
way of determining compatibility?

Thanks for any enlightenment,
Ben