I am now vascillating between the Tiger Shark and the Headhunter Diver. Apparently the Tiger Shark was/is (don't know) out of production because a critical parts supplier could no longer supply a specific part. Heard??? That has been remedied and they are back in production. However, in checking various random sites for the machine, a lot of them advertise the machine but say Out of Stock.
Compaing the two.. The TS requires that you open the case to adjust sensitivity, volume, and threshold with internal pots. Folks on the Tesoro part of the forum don't consider that to be an issue. They set it and use it. It does have a saltwater mode and lots say it works fine in saltwater which is unusual for a single frequency VLF machine. The shaft is good enough that you don't have to add another $100 to get one that works and is convertible from diving to wading. The Tesoro Lifetime warranty is worth a lot when operating a machine underwater. Read one post where a new machine was taken to a vacation resort and in 25 meters of water it leaked badly. If you close both latches on the case simultaneously, after replacing batteries etc, it tends to stress the " O" ring evenly and maintains the water tight integrity better. The street price in most places is $599.20. If someone has other major points they have discovered I'd like to see what you have found.
The HH Diver has had some issues with maintaining water tight integrity because of customer mishandling. The plastic used on the headphone/electronics is susceptible to hairline fractures if dropped or banged. Duh! But a water machine tends to get handled a little more roughly because of the other equipment and environment in which it operates. I am told that a different type of material for the headphones/electronics is going to be used and that should eliminate that problem. However, you must now buy used as they are out of production until the new type material is available and in production. They are reported to be sensitive and stable and how can you beat no electronic control box, it's all in the headphone so you carry only the shaft and coil, and the headphones, and know need to worry about getting a different shaft. I didn't see hardly any HH DIvers listed for sale but I think they are about the same price as the Tesoro.
I may keep the Excalibur but there's no doubt a back-up underwater machine is necessary if you are going to count on the Excal. Jim