Unless a person has very DEEP pockets the word margin should not be part of their vocabulary.There is never a sure thing in the stock market especially stocks that can be prone to heavy manipulation like startup bios.This is exactly how wealth is transferred to the rich.Always always always use settled funds for your investments.
Agree on margin. Not only can the brokerage's force you to sell, you allow them to loan your shares for shorting. Finally, going on margin, in my opinion, is a sign of impatience and lack of discipline. Not good characteristics for successful investing.