Omer, to Neil's point, do the outside investors have additional rights that other LLC members don't have? This is less common with LLCs than with corporations selling preferred shares... but it does happen. This can be used to argue a lower valuation for your shares. Also, the size and timing of that investment matters.
e.g., a $500K investment 2 months ago with no additional rights to the investor is more challenging than a $50K investment 2 years ago with extra liquidation rights.
Martin, Omer is trying to avoid the scenario where he has to pay ordinary income tax at exercise... which can be more than twice long term capital gains tax.