The Venoms are probably a better battery. I would not leave them or any LiPo fully charged for more than a few days. My fear would be that the puffy cell might go ballistic when put under stress and burn your vehicle/house down (or up). If your were to leave them longer, as they are puffing anyway, they could easily go up in flames. It would be advisable to discharge them to 3.7v and not take the risk.