I never owned the Golden Sabre but from what I've seen of the other older Sabre machines is they're pretty much the same in depth as the newest Silver uMax. See, basically what they did with the uMax is added more miniaturized electronic components to make a smaller box. But actually, the functional depth is about the same.
You'll read where some claim the new uMax is deeper than the old Sabre models. If there really were a difference (I didn't notice it) then it would be due to the coils now used on the uMax machines. The new spoke coils are larger and therefore deeper than the old donut coils.
Take a Golden Sabre and put a new 9x8 or 12x10 concentric uMax coil on it and I'd expect it to beat any new Silver uMax with its 8" concentric stock coil. You see, Tesoros really haven't changed all that much as far as the electronics are concerned. The biggest change has been in the coils, not in the electronics that cause the depth.
The Golden has notch which can be useful in super trashy places.
An awful lot about this hobby is psychological and not actual. People who believe their detectors are deep and very good will find far more than those who doubt their machine's abilities. This is the main reason dealers hate to take in on trade scratched detectors. The machine may be perfect but in the mind a person is somewhat ashamed of his detector and this causes him to not properly concentrate while hunting which means fewer finds.
Some people are highly affected by comments made on the various Forums. If someone posts that one brand is a piece of junk some will get very upset with that person but within 3 months will sell their machines and move on to another brand. The posting may have been pure BS but in the mind if took root and destroyed those persons faith in their machines. This caused them to make fewer good finds and falsely assume that that commentor was correct.
I'd say 90% of this hobby is psychological in nature.