Cheaper models are switch on and go, though the 45 has an adjustable gain control.
Built like tanks and rather heavy, though an improvement on the models they replace.
Do suit medium mineralisation better. If in the U.S. I would pick an American detector in the same price range as the Saxon's depth is unlikely to be better and the U.S. warranties are hard to beat. The advantage is that they do work well in heavy iron conditions. On a beach where a storm had moved some sand dunes sideways leaving flat areas covered in rusty nails (and lots of coins) the Saxon could be swept with only coins and the nails with 90 degree bends sounding off which was better than the other big brand machines I tried to use.
So if you have a site that you think might suit the 45 could be a good buy.
The Saxon X1 Ultradepth is a different kettle of fish. Similar in design to the famous Arado 120, 120b and 130 designs but deeper. U.K. price is £1700 which puts it above the new Arado 320 which is the latest in this type of detector ie all metal/non motion primary search mode with ferrous I.D. by meter.
Again rather heavy compared to most modern machines and the larger than standard coil can act a bit like a sail in high winds.
Lots got sold to Italy as they are a serious pro machine rather than a park coinshooter. Single frequency which together with the larger coil size means not suited to wet sand.
If you don't mind checking out every signal and have the right site it could be a good choice. The ground adjustment control puts it in a higher league than the Arado 120/130's. Again if I was in the States I would go for the Nautilus version of this type of detector. The split audio does a similar job to the meter of the Ultradepth, there's a better coil choice, weight/balance is better if you have the latest Whites shaft version and the detector isn't going to have to go abroad for tune up or repair.
Cost is also a big consideration with the Nautilus DMC and ALL coil sizes coming in at half the price of the Ultradepth.
I've not helped our balance of payments problem here (Britains in deep doo) but if you want bangs for your bucks you need to shop at home. I've no longer got a Saxon X-1 but I do have two Nautilus DMC's which says it all.