in another thread a question was askes about a 19 seer system and you replied:

In most climates, the huge premium you pay for the ultimate equipment will have NO economic payback. There could be some advantages in comfort & humidity control, but don't look for those thousands back in energy savings usually. Putting that extra towards windows, window tint, insulation, duct sealing, all could pay back so much faster.

At what rating will you realise a savings that will be cost effective? depends on the climate doesnt it?