Well, I checked the faq page very quickly. Seems like you have been copy-pasting from r3mix.net regarding nspsytune...

It's not exactly correct.
--nspsytune doesn't use -X0 by default in CBR mode (nor vbr).
If you use just a basic cbr/vbr line with nspsytune (no preset), it uses -X1. You can check this with --verbose switch.
It'll show:
"experimental X=1 Y=0 Z=1"
Also it's good that you tell about Lame's better joint-stereo, but it isn't exactly true that:"Other CODECs just use mid/side frames all the way, thus destroying the stereo image on very "stereo- independent" songs."
Other codecs use also m/s and l/r -frames when encoding with joint-stereo.
Not sure also about the --nssafejoint description. If you say it keeps the stereo image "tight", it gives in my opinion just the opposite impression it should..