What am I doing wrong with this FFT?

[Gribouillis]

Do you know by chance why the FFT amplitudes are the not the same for the four?

I think it is the same effect. If you take the DFT of x[k] = exp(2 pi i k / N), you get spikes that all have the same amplitude, but if you take the DFT of x[k] = exp(i omega k) where omega is not a multiple of 2 pi / N, you get a "smooth spike" which amplitude varies. You can actually compute the DFT by hand and get a closed formula for the result and you will see that the amplitude varies. The conserved quantity is the L^2 norm (Plancherel theorem), not the maximal amplitude.