I had placed my FREQUENCY in the calculation rather than NN - sample count.

That and switching to AudioWindowBlackmanHarris1024 - I get this on PJRC/sinewave:
Freq:100.00 CalcFreq:99.93 bMax=33 bMaxId=2 bStart=0 bAscDur=2 bDecDur=2 bSecond= 0
Freq:200.00 CalcFreq:199.91 bMax=33 bMaxId=5 bStart=2 bAscDur=3 bDecDur=1 bSecond= 0
Freq:400.00 CalcFreq:400.12 bMax=34 bMaxId=9 bStart=7 bAscDur=2 bDecDur=2 bSecond= 0
Freq:800.00 CalcFreq:799.94 bMax=32 bMaxId=19 bStart=16 bAscDur=3 bDecDur=1 bSecond= 0
Freq:1600.00 CalcFreq:1600.07 bMax=34 bMaxId=37 bStart=35 bAscDur=2 bDecDur=1 bSecond= 0
Freq:3200.00 CalcFreq:3200.11 bMax=34 bMaxId=74 bStart=72 bAscDur=2 bDecDur=2 bSecond= 0
I'll save my sketch and output and then repeat with KPC_FFT code shortly.