I also have the original MOH, so this is valuable information. I understand that the new one is better now but it may burn-in more, 50 or 100 hours are not unusual for full burn-in. It becomes increasingly difficult to hear differences, so this is rather floating.
If you just had the MOH on, it seems more like warming up than burn-in. For a basic burn-in you need to play it for 24 hours. When I received my MOH five years ago, I was not attentive to the burn-in process, so I have no idea of how long time it took.
There is a reason why it is important to consider burn-in. If you borrow a product or buy it with a return option and test it: the result may be misleading, leading to a wrong decision, if you dont know the state of burn-in. For example: borrow two cables from a shop where one is well burnt in and the other new. The new one has to be much better to sound better from the beginning, and may even sound worse.
Of course it is easy to make mistakes in these auditions because your own mood changes and one may be affected by expectations. A few times I have been so critical of myself that auditioning became impossible. I heard a difference but it may only be my expectation? You try again and again, becomes anxious and tired and looses your sensibility. Now, it is time to turn off the system and return some other day.