Drivers may possibly need to improve as one user posted a difference in benchmark between morphOS & OS4.x but I am no programmer so maybe someone can explain the difference in benchmark figures.
You could test MorphOS 1.4.5 in your machine. It's no longer possible to register but since demo is limited to 2 hours you'll have enough time to test stuff. OWB 1.16 works on MorphOS PowerUp :-) If you need help I did a small guide (I tested it quite a lot with A3000/A4000 and not so much with A1200):
http://almogavar.blogspot.com.es/2011/06/instalacion-de-morphos-en-un-amiga.htmlThen you could install a more or less recent MUI4 beta and an updated Ambient (more similar to 2.x ones). Change MUI menu delay to 0seconds too. IIRC there was also a default font that wasn't available and with default config it worked slower than it should.
Now that RoadShow is available you could also install RoadShow.