But I had to answer this one. Everyone who beach hunts think that they have to have a PI. I thought so many years ago and got my hands on an Eric Foster machine. His are the best ones out there. However, I did not keep it very long. One day I found 3 miles of wire in pieces no larger than 2 inches long....you dig a tremendous amount. There is another Metal Detecting site....not nearly as good as this one, on which there is a PI forum. You might get some good information on there. Although there is a place for PI machines, you get tired of digging...I mean physically exhausted.
At the beach you hate to give up a target, and sometimes they are so deep, only to find a tiny piece of rusty wire from the beach fences. They keep falling through your scoop...we all have to learn the hard way.
There is a guy ( John from Edmonton) who I believe uses the Garrets PI....in some frigid conditions...I believe he does quite well with that machine...whatever you decide, Good luck