Just some thoughts..
Most glider software does factor in wind however (calculated from drift while thermalling/circling). I agree they are pretty accurate..
However, in a power plane I'm happy with just having a rough (and conservative) number in my head of 'x miles per x thousand feet' and using that with the existing distance iFly distance circles.
No wind.. fly best glide speed, tailwind slow down a bit and expect a little better distance, head wind speed up a little and expect a little worse. I would not be comfortable with flying a final glide based upon gps calculator since (i) unlike in my glider I haven't worked up to it and tested/gained comfort in it's accuracy, (ii) I'm going to quit trying at a much higher alititude and pick a field before it picks itself for me.