Koo you are incorrect in your assertion that the warrants will become worthless in a takeover.  The RVX warrants are an obligation of the company and not market instruments (like some types of options) and as such would become an obligation of any acquirer of the company.  Also don't forget RVX or a successor receives the strike price in any exercise.  In any event if RVX were to receive a take over bid both the shares and the warrants would continue to trade even after the bid was accepted for a specified amount of time with the shares likely trading somewhere around the bid price and the warrants (assuming the bid puts them in the money) would trade around the bid price less the strike price.  

JMO but quite frankly I think the warrants right now are a screaming deal if you believe in RVX and at roughly 3 warrants for one share the trade of selling some shares and buying warrants with the proceeds can increase your upside potential significantly.  Just do the math.  Alternatively as others have suggested selling some shares and keeping some cash and buying some warrants can be a way to mitigate risk.  For me I have been buying warrants to cheaply increase my call on potential RVX success.  With 4 year expiration there is plenty of time for the shares to react if success is found with BetOnMace.  Again JMO