you're looking for my opinions in general and not for someone to confirm your decision to spend the bucks on one.
First, about the BigFoot coils in general. They are a unique aftermarket coil design that is intended to provide coverage on the side-to-side sweep. They do not really provide better depth, just coverage. matter of fact, I speak with many Bigfoot coil users who confirm that the depth isn't as good as their standard coils in many places, but they like the coverage.
I checked out the Bigfoot coils when they were first introduced, and I still hunt with some friends who use a Bigfoot coil at the beach, mainly. When I do, they never end up with more finds that would be coil-related.
As for the Prizm series, I take a different look at them to begin with. Your Prizm V, just like my IDX Pro or any other slow-motion, two-filter type detector, is really at its best when searching trashier sites compared with a faster-sweep model. For greater versatiltity and field results, using a smaller-than-stock coil on a slower-sweep model helps up the return in trashier and brushier locations.
Unfortunately, White's doesn't have a smaller coil for your Prizm V. So, if you are determined to get an accessory coil for the Prizm, you might try the Bigfoot.
I would strongly recommend, however, that you try one out before you buy it. Then, if you do, make sure you have some sort of a return policy for the coil in case it just doens't perform well for you.
Remember that the Prizm's have a different circuitry design and although there is access to a GB trimmer, it doesn't function for both the All Metal/Pinpoint mode and Discriminate mode like the Classic's or many competitor's models. It is important to be aware that many makes and models that rely on preset GB's will not function well with some different sizes and typrs of coils.
Sorry I am not of more help than that.
Monte
