For my new home, I want to get a heat pump with the new R-410 Puron coolant. The home will be about 2750 ft^2 on the ground floor slab with either cathedral ceilings or upstairs under a generally gabled roof (think of a long, 1-1/2 story Cape Cod.) The insulation will be spray foam everywhere, so that fact that there is little attic space is most irrelevant, with a target net R on the non-window/door area of the walls and roof as R-19 & R-30 respectively. The window area will only be about 8% of the ground floor slab area, and will be double glazed low-E for the most part, and of them, about 1/4 are not north or south facing (under quite a long eave.) The climate is borderline South and South-Central with 500 & 2000 heating & cooling degree days, respectively, with amongst the highest wet bulb temperatures imaginable (Southeast LA.)

It seems that there are a plethora of manufacturers these days, and within each manufacturer, a number of lines of HVAC units (differentiated by net SEER or COP rating and multiple level ability, more or less), and of course the tonnage rating. I have a hunch that when I get bids, every HVAC sub is going to want to push his favorite supplier. So it seems that the best course of action is to know what SEER/COP rating to shoot for that makes the most economic sense, and then consider those features that are important, to get the recommended line for each manufacturer. I suppose that the HVAC sub would do an analysis of the required tonnage, but it seems that it should be a relatively easy formula as Q = (Σ A/R)*(max ÎT) * (some humidity factor). Some insight as to what this tonnage would probably end up being would be helpful.

So I would like to know what manufacturers and lines, as well as features that I should be on the lookout for, both as positive or negative.