First Alpha 2160 has come of the production line in New Zealand.
Would think the 2160 would be best for 2000' and 40C. The 2120 is ok up to elevations of 1500' and 20C at AUW but would struggle higher and hotter.
The aeroclub I used to work at in New Zealand bought several 2-3 years ago and all had/have corrosion issues- Alpha Aviation are working on a remedy for this. I believe the new build Alpha's will be finished to a better standard.