We have one beek in our association in NE Ohio who overwinters all of his colonies in single deeps. He is geared toward local pollination, so his goal is to have healthy singles to move to the orchards in early spring.
He has moderate winter losses, but to achieve this, he spends considerable time and resources in heavy feeding in the fall and early spring.
He stresses that successful overwintering in single deeps is an attainable option, but you can't just walk away and leave them to fend for themselves, they will need your help if you want to keep your losses low. If you don't have the time or inclination to be extremely attentive to the colonies needs then it would be much simpler to leave the extra stores in place and overwinter in double deeps or three mediums.
To everything there is a season....