The people in the States that did buy the Vista RG750 were not to happy with them. There should be a few reports around.
The Golden Mask machines will not be an upgrade for many. They are a very good buy for the price but If you already have a top of range machine you will find them heavier than many and with a restricted range of coils. Plus many are not happy with the re chargable only system of the moment ie no battery back up. I don't think they have modified the discrim. range yet so if you want to detect a park or top of the beach at a high discrimination level you will have to wait for a modified machine.
The Blisstool LTC48, also Bulgarian seems to be better on silver and lead (so probably gold as well) from early reports. Other machines that offer high performance at a lower price point are the Rutus Draco and Proxima's, Ducat models, Demet who do pulse, motion VLF's and the Diogenit (motion/non motion). All are Polish.
Atlantis seem to have sorted the Imperator and have the Supersonic XM-4600b for hoards/caves/cavities.
There's a whole raft on new machines and at last the build quality/reliability problems of the past seem to be getting sorted BUT, often these machines are designed to impress with impressive air test figures so the coils tend to be larger than those of the old main brands. If you have highly contaminated or busy sites check that there's a smaller coil available.