I have been trying to not, respond to topics here very much the last couple years, because there is so much disagreement, even though in most cases it is done in a nice way. But sometimes it is hard not to say something.
The whites PI is a very good salt water detector. In the honest tests that I have done, and have read on line, it is one of the deepest going. Yes in my opinion deeper than the Excalibur, but have not compared to the Garrett. Yes you do have to dig everything. But that makes you good at digging. If everyone dug all the targets that are out in the water, you end up with less and less trash, if it is a beach you will be going to often, by digging out all the trash, it gets easier each time. It will get to a point where you are digging more good targets (new lost items) than trash. Also it makes treasure hunters look good to get all those sharp nasty targets out of the water.
I have had mine for 17 years, it still works great and has never leaked. Mine has the weighted coil. To stop the coil from flopping around, White's has a kit that locks it in place. The new Surf PI dual field has a new coil called near zero buoyancy. It is like the older weighted coil. I do think I will be buying a new PI dual field this year.
This is all my opinion, But twice I have found rings where I had a friend I was hunting with, who uses a Excalibur check the signal and got nothing. I have not hunted with anyone that uses a Garrett, so do not know how it will compare. I do know that most all (not all) the targets that everyone digs, can be found with any of the quality detectors that you read about on here.