Although V-Lowers have their use, they take a great deal of time to set-up and that needs to be factored into your decision. This technique requires a rescue vest, don't jury rig a quick release system. A major advantage with this technique is the ability to use pinpoint precision in placing a large platform like a raft at the accident scene in a reasonably safe manner. Many fire departments like this technique just for that reason.
The V-Lower is a technique for placing a rescuer or boat in a precise location in a rapid. They take a fair amount of time to set-up and are fairly complex. They are a poor choice for a heads down rescue but are an excellent choice where you have the time. Lowering an attached swimmer mandates the use of a rescue vest. The rescuer person in the water needs to clearly communicate their needs (like navigation) to the puppet handlers on shore. A quick release system is required even on a boat. Many Fire Departments use this technique as it provides a stable rescue platform and they don't get the chance to practice whitewater boating skills. Boaters on the other hand favor using a boat without rope attached since they have the necessary skills and it is much faster to set-up.