Babysitter,
I understand drafts, but this is constant, forced convective flow. And what's to say that HagilSight didn't test it both ways and found the fan better for most purposes? It just seems like a lot of what we call "armchair quarterbacking." If they didn't have a fan in there, everyone would be on here complaining that the device didn't come into thermal equilibrium with the test environment quickly enough. And my very modest experience with the devices are that once one measures in the 100 uV range, the lab and devices need to be as temperature stable as the meter anyway, so I still am not seeing the huge downside to the fan.
It just seems like this huge assumption that the HagilSight failed to due their due diligence with the design, so the only remaining argument I could understand was noise.
Just my 0.02 ...