We sell Amana and have installed a number of two stage HP's. We
typically use a White Rogers stat, though I can't tell you the model off
the top of my head and don't feel inclined to go check right now.
Anyhow, I have often thought about exactly the same thing. The WR stat
does "learn" cycle times and how long t takes to sense any temp change
when it decides to kick stage two in. On Amana two stage you drop about
1/3 capacity in low stage. It would be easy enough to rig a HP to only
run in high on heating. I have brought up the idea, but we have never
had any customer complaints, so never tried it. Anyway, all you would
have to do is have a relay that is powered from the 'Blue" wire on the
stat (which powers in heat mode and is usually only used with Rheem/Ruud
HP's) Just have that relay jump Y1 and Y2 togther when it is powered ,
which is only in heat. BTW, I have toyed with the idea of putting a 16
SEER two stage Amana 3 ton HP in my house, but as long as the antique
Trane keeps on going I probaby will never do it. (Waiting for the
distributor to get one dinged up with only cosmetic damage that they
will make a deal on (: Larry