The new R-410 units will run in higher temps much better. They are also typically more energy efficient!
Did you get a heat pump model? That would be nice if you full time, and are in campgrounds in the winter.
Also if the older units where not washed on a regular basis, they can lose about 5% - 10% of their ability to exchange the heat due to soil on the coils. Wash the outside coil with a garden hose once a year, and it will return to peak performance!
And it is possible that your older units where slightly low on freon. This can drop their rated capacity by 10% or more.
Good luck with the new units!
Fred.
