I have upgrade my iBook G4 to SSD on 2013/10/11 Fri. The disk access feels much faster than the internal 4200RPM IDE or an external FireWire 7200RPM 3.5″ WD 160GB IDE. My left hand also feels much cooler when typing on this notebook.
Here is the disk test result by Xbench 1.3 on MacOS 10.3.9. The bottle neck should be IDE and the SSD to IDE convertor. A SSD with native Sata 2/3 will perform even better. Compare to other IDE drive, the transfer rate is improved. Also, the SSD should perform better on access time than hard drive.