It's also important to know that the save option is greyed out as long as poseidon doesn't notice any changes in your settings. So if you removed poseidon from the flashrom,
and the save-option is still greyed out, make some unimportant changes in your settings, and see if the save option becomes available.
BTW 1 important advantage of keeping poseidon in the flashrom is that you can boot from usb masstorage devices.
If you keep it in the flashrom, you don't need psdstackloader in startup-sequence/user-startup anymore,
but when you change your settings in trident and saved them, you must reflash the flashrom with the new settings file (ENVARC:psdstackloader).
EDIT: This also goes for other poseidon files, for example when you install a new version of poseidon, you must reflash the ROM after installation.
Regards,
Lloyd