I dont know about the other brands but the sand shark is a super machine,I use it on the beach,in the ocean whatever.You can walk from the dry sand into the ocean neck deep and the threshold will change so little you might not even notice.You are digging tiny fish hooks,sorry. sometimes iron gives a zip zip and you know,but sometimes it gives a hard solid signal like a coin.Usually solid signals are solid objects,not to rusty/flakey there are alot of iron flakes on wrightsville but they are not solid.(think pine bark).They have a very low mellow tone.They are right on the surface so I was pleased to see a PI with no disc give this much info on targets. I use the 8" coil and I want to say its a little small,I have found some deep stuff but I was listening to the threshold very carefully and if I even thought I heard something we scraped a few inches of sand off and rechecked,most of the time it was a target.I pulled over 60 .50 cal machine gun projectiles out of the beach with this method.I use the vco mode only so far and I like it so I cant offer advise on normal mode.cant tell much difference in the pulse width adjustment, I use preset. Cant go wrong with sand shark.