i was thinking alot about this and i think the question isn't if we should take Starfarer with or without Gemini upgrade, but to which one the LTI will be more worty (as we will be able to get a 2'nd Starfarer in the game ), and when i am thinking about this like this, it is a much easier deciesion, lets see both the options.
1) regualr starfarer , will mostly go in safe zone with low risk level, low risk = cheap insurance.
2) Gemini upgrade , will mostly go in less safe area's with higher risk leve , high risk = more expesive insurance.
even the fact we don't know all about the insurance, still looks like a better deal for the Gemini.
also i just look great. (something like a full tanker in mad max I)