I must object about Geneva here. While I agree Geneva
is extremely compatible, it is not close to the speed
of either N.AES or MagiC. Try CAB on Geneva for example...
That said, I guess it might come down to what speed you
are talking about. Geneva is only an AES (that is where I
think slowness is). Geneva running on top of TOS
might give good results for CPU-intensive stuff,
but then they are practically running under TOS.