Os 3.9 (not shure about 3.5) uses a new icon engine that practically mandates the use of RTG. Picasso II or IV work very nicely. Without RTG, icons and workbench use is very sluggish.
However, with RTG, OS 3.9 looks as modern as any other OS. On my setup, OS 3.9 is very responsive. I also have a 3000 with Picasso II and 8 Megs of fast memeory (no accelerator). It is a little slower but still very pleasant to use.
