Seems like a bigger one would only be more efficient.
The smallest ones are almost the most efficient ones in the range.
I’m not sure why this is, and whether it generalises to house-size ducted systems, but it’s pretty striking nonetheless because it’s the exact opposite of most heat related systems I can think of.
Thus, smaller units, more spread out, have access to more heat?
It’s fascinating to even see the huge increase in switchable units - running your 4/5 ton unit at 4 tons is much more efficient. (Usually)