But he said there is absolutely no problem to change the fans if you want less noise or higher performance.
Did you ask if this would void their warranty? You can be pretty sure it does. So that is why I think it's up to them to provide the best components in the first place.
Also, they really need to post something on their website letting people know how long it will take them to accept a faulty miner for return, how long they will take to repair and return.