That is why I propose that when switching your DoW retainer to another DoW class (for the sake of gearing and reaching the new level cap), their level progress should not be fully reset as there is no exploitation for switching amongst these classes.

For specifics on ideas on DoW class change, say if you wanted to switch from a lv.50 DRG to say a lv.30 DRK (because your DRK is only lv.30) your retainer should be resetted to lv.25 DRK. But it shouldn't be resetted all the way. In fact, if you had a lv.50 DRG and a lv.60 DRK and resetted your retainer class, it should still stay lv.50 (and not a free lv.55) where you can level it back up). This way your progress isn't completely lost and it's very easy to switch your retainer to another DoW class if you have already put in the effort to level up the class yourself on your main character.

Finally, sorry for all the replies to myself but SE doesn't like my lenghty forum posts so I need to break it up.