I was told by a DIRT member "if it's not broken don't fix it" .
What? That is one of the more irresponsible responses I've heard. Is this person going to put in writing that they personally will repair or replace all equipment (including your home) if anything goes wrong? What if the adapter overheats because it is under rated and instead of failing open (simply stops working which I would believe to be 'typical') it fails to the point of melting or even fire?
Now, to be honest, in today's electronics (unless a really cheap or POS knock-off) you may not have to really worry about this minor current draw difference affecting performance. But if the 4K Joey starts to draw more than the power supply can provide then it may cause unknown issues. If I remember correctly, higher than rated current draw will lower the effective voltage the power supply delivers which could affect the way the Joey functions.
This is not like a phone charger. Where if you use a low current charger the phone adapts and only draws what it can; simply takes longer to charge. This adapter provides the working voltage/current to the Joey. I would think the DIRT member would at least want customers to use the supplied equipment for peak performance, if not simply for possible liability reasons.