I only went to lvl 99 cos I wanted an easy win and to say "All of my characters are lvl 99 " but while training the fun did wear off pretty quick so the sidequests rocked. Much fun. You should be fine though if you keep going like I assume you have been.

My biggest disappointment in disk 4 was that all the fun places from the previous disks (Fossil Roo) were closed off and I couldn't go back to them...