dustcover up, down or off

if you don't hear a difference, do what you want...if you do hear a difference, the answer is the same.

if you don't hear a difference, do what you want...if you do hear a difference, the answer is the same

Exactly.

but I recently read an opinion

And it was exactly that , an opinion. Nothing more.

What works for one may not work for another person....somethings just have to be tried first before an opinion can be made.

I agree with what the others have said so far, with one caveat: If there is even a remote possibility that the dust cover could fall down while playing a record, I would either play with it down or removed entirely, as the effect of the dustcover slamming down could easily cause damage to your record and/or the stylus.

My two cents worth.