No problems with the Tesoro Tiger Shark at all. It has a salt water mode and it works well. Very good on batteries and very easy and stable to use fresh or salt water. You can change coils with this detector and it has a Lifetime Warranty. Though I don't think you'll ever need it. I never have. The turn around time if you ever send it in, depends on the time of year as with most manufactures. They get swamped in the summer.
The Stingray II was no good in salt water. In fresh water it was almost too hot on tiny objects and gold chains. Tiny also means bird shot. Small gold chains have no weight to them and the time spent digging bird shot could better be spend swinging for the ring.