I agree this is an important aspect to consider. However I don't think it would affect the OP's estimate of the value of the option grant itself. It would inste

I agree this is an important aspect to consider. However I don't think it would affect the OP's estimate of the value of the option grant itself. It would instead affect the price payed by accepting a below market salary. I.e. the 'real option to leave' can affect the ROI but not absolute return.