Interesting, last time I was using my A1200 heavily I'd have to keep running a util to defrag and reclaim the RAM, chip RAM in particular used to lose 200K-400k or so pretty quickly. Think the util I was using was called "memory hogs" or something like that.
Now if you want a perfect memory allocation system, howabout if it was divided up into 64KB banks, and each program was given it's own 64KB bank. If you had 10 banks that would be 640K which ought to be enough for anyone.. :-P
(Just kidding of course)