Good evening Aero, :)

I think your synopsis sounds very reasonable.

Sadly, I have actually encountered (a few times) where the options are not "intelligent" ie GSM + 3G literally mean both or none.

I dunno if reflashing your phone might alleviate this issue, but I might suggest reading up on more recent firmwares that may have been released for your phone.

Perhaps in the later releases(if any) the 3G AND GSM option has been adapted to [3G AND GSM] OR [GSM ONLY].

Who knows?!:confused:

I suggest checking the MAIN and FS file versions you have and poke around on the forum to see what info you may find out about them.
And as usual there is also our good old friend Google... ;)

I hope you find what you are looking for!

Take care Aero, and best of luck! :)