Well looking up the specs for an Amana Budget system [1] that is more typical for what you would find in American home (mini Splits are rare here, and normally installed in Garages and Shops, not primary residences ) 1.5 Ton unit COP drops to 1.4 @ -5 and only matches the efficiency of the minisplit you linked @ 10 degrees
if I look at the high end an Amana System[2] and 2 Ton unit (which is more common size in the US) COP drops to 1.7 @ -5 and drops to about 2 at single digits.