[turbo6bar]

Gosh, that's a lot of freon to lose in 2 months. The leak must be quite large. I'd get a pro to do a leak check and go from there.

As far as getting the unit replaced, I'd go with R-22, any brand (installer is more important), and SEER 13, because that's the lowest rating you can get. You'll pay a good premium for the higher SEER rating equipment and Puron refrigerant requires more installation time, so the final price is higher. You can do a cost analysis, but at this point I do not feel the high efficiency units are cost effective. Spend the bucks on better attic insulation.