Re. Gold Rush, our weather does not consistently allow GR to fully ripen in some years. Last year I picked mine when the forecast said low temp would be 24-25F.
It appears damage to apples that still hang on trees occurs when temp is 21 or lower. I did not want to wait to find out. Mine were not fully ripe but tasted good. Another good thing is that not fully ripe apples last a lot longer in storage. I still have one GR left in the fridge. It is worth growing,