What is the problem with the TY4 OS? I am thinking of buying it and was under the impression that it was reliable. What should I know about any problems? Do you have a link where you've already posted your complaints? Thank you. FYI I decided against the Ketron Audya because of the OS, against the Korg pa3x because some say the sound is not as good as TY and now I'm curious what I've missed in my research. Thank you.