@CodeSmith
I'm surprised no-one's mentioned this - the biggest memory hog on OS4 (and I bet it is on MOS too) will most probably be the native code caches for the 68K JIT translators. The bigger the caches, the more the JIT benefits.
Not on MorphOS, Trance is very modest in memory usage. Naturally it depends on the applications you run, but typically only few megabytes of memory is used. But there are no extra "caches" to hog the memory, only the required memory is used.
I'm currently running AmTelnet, FACTS, PFS3, lots of 3rd party 68k libraries and classes, IBrowse 2.3, and the Trance total memory usage is 2781KB.
1214592512 bytes available. :-)
I can't comment on Petunia memory usage.