OBN, you are the man when it comes to Excal mods.
People in BBS circles owe you a ton of gratitude for spear heading mods and fixes for the Excals, and you are a wealth of information.
Far as the Tornados go, yep...Very hard to find a 8 or 10" used, which speaks well of how good of coils they are. I'd say the 8" is even harder to find used than the 10". Hey, anybody know....Could you order an Elite or GT with the 8" Tornado on it or did they only come with the 10"? Even if you could get one new with the 8" I bet most opted for the 10" and that would make sense as to how hard the 8" is to come by used.
I posted a question for Ralph at Sunray in his forum as to if he plans to still make the S-5, 8", and S-12 BBS coils. I would figure he would since the Excals are still being made and the S-12 for one seems very popular among Excal water hunters. Wonder if Coiltek plans to keep making their WOT and other BBS coils as well? And once again I'd figure they would because the WOT also seems very popular among Excal water hunters. Throw into the mix all the various coil compatible Sovereigns made for 20 years and there is a huge market of potential coil buyers out there, discontinued GT or not.
I suspect Detech will continue to make BBS coils as they make coils like the SEF for some long discontinued and never nearly as popular detectors as the Sovereign is. Even if Detech stopped making BBS versions of their coils I bet if a group buy through Kellyco was pre-paid Detech would probably happily run off a batch to fill and order.
I'd encourage anybody who can swing the cash to get your 8 or 10" Tornados while Minelab will still make them to fill orders up to I think the last day of December. Way I think I read it so long as you get your order in with a dealer by the deadline Minelab will produce a GT, SE, or Tornados to ship to them. After that it's either used (good luck with that) or finding a dealer who has new ones lurking around in his stock
Once I get my hands on an 8" Tornado and a 13" Ultimate I can rest easier. Those are the two coils I want to complete my line up for my GT. After I aquire those then I'm going to start picking up some used Sovereigns. First purchase is going to be the original as I'm hearing some very interesting things privately about it's depth potential that I want to investigate for myself. I plan to down the road have a fleet of Sovereigns, like say 3 to 5, sitting around, and might even try to eventually collect every coil made for them (besides the heavy old 8 and 10" BBS coils made before the Tornados). I'm thinking WOT, maybe a 12 and 14" Excelerator, the 4.5x7, the 10x14, and a few others. For sure though I want an 8" Tornado and 13" Ultimate in my arsenal.
By the way, just ran across a blurb in the classified section where a guy with a long history (by the looks of it) of fixing Sovereigns says the only potential aging issue that might need "tuned up" on a Sovereign is the large capacitors on the board. Otherwise there really ain't much to need serviced on them. Makes sense, as I know capacitors can degrade over time due to the insulation between the charged surfaces in them breaking down with age. Just throwing that out there for anybody who might have a non-working or not very stable Sovereign laying around. You might want to find somebody who knows how to solder to throw the large capacitors (should be blue I think) back on the board and see if that corrects any issues. If you find your unit isn't allowing you to run at as high of sensitivity levels as in the past or is somewhat fussy then this could be the problem and a real easy fix.