Buy one of the more modern machines, which are still very cheap - and give it a whirl.
Costs nothing to download. If you do not enjoy the experience that MorphOS offers don't buy it, you still have a perfectly good Mac there to either use under another OS, or sell off at a price close/equal to what you paid for it.
All it'd cost you is the media to burn the OS onto if you were unhappy with it.
MOS is a very good experience, IMO - and the demo gives a very good feel of what it's capable of.