Test the performance on loading the OPL database (OPL-update). When mysql was first switching to InnoDB that was very slow compared to MyISAM so we just shelved the switchover to InnoDB for the time being. I'm not aware that anyone else has actually tested this recently. Also OPL-update is not that time critical so if that is the only place there is slow performance then we would probably switch to InnoDB -- apparently it has some reliability advantages.
It's quite possible that the situation has changed over the last few years in terms of the relative speeds. Let us know what you find out.