I agree that the ET2 has (probably) the only thouroughly intelligent VTA adjustment, though it isn't / wasn't without problems in my setup. It used / uses very low torque direct wires, lower torque than original. With my arm lateral levelness was affected by the VTA setting, which it shouldn't by concept. The block screws are adjusted for equal torque... I will have to check it sooner or later with the "feeler" gauges.
I think the main difference and advantage is regarding the non changing overhang.
Non changing VTF is a question of having the centre of gravity aligned with the vertical bearing when floating the arm. This is not an exclusive feature of the ET2 arm, there are more that are concipied this way AFAIR. Fine-tuning this precis balance is however most easy on the ET 2. The WTA Signature (which I own too) is extreme in that regard, as the vertical bearing is at the lower end of the nylon threads, where the threads vertically leave the paddle block (which swims in silicone oil). Way below the center of gravity.
To have the statical center of gravity aligned with the vertical (or horizontal...) bearing axis is, BTW, a solution for only half of the problem: Elongating the I-beam until "mirroring" the cartridge/arm masses and lever lengths potentially aligns also the dynamic center of gravity into the vertical bearing axis. This reduces the dynamic, horizontally pulling forces on the bearing when the arm moves up and down with warps. Ie. it reduces a source of "microdynamically varying offset" with warps - and or vertical modulation...I have not seen a discussion of this aspect anywere yet, but it's a weak point IMO of the WTA and unipivot arms. If one considers the tiny metal point contact (rather a microscopically short metal string) of a unipivot this makes one scratch ones head, because this interface is "elastic by design" which "even" a ball bearing is, on a microscopic level.There is much talk about the elasticity of air bearings - but actually the "better" or more close toleranced ones are rather stiff (plus being chatter / variation free) compared to the situation in metal bearings, at least compared to unipivots.
I think the main difference and advantage is regarding the non changing overhang.
Non changing VTF is a question of having the centre of gravity aligned with the vertical bearing when floating the arm. This is not an exclusive feature of the ET2 arm, there are more that are concipied this way AFAIR. Fine-tuning this precis balance is however most easy on the ET 2. The WTA Signature (which I own too) is extreme in that regard, as the vertical bearing is at the lower end of the nylon threads, where the threads vertically leave the paddle block (which swims in silicone oil). Way below the center of gravity.
To have the statical center of gravity aligned with the vertical (or horizontal...) bearing axis is, BTW, a solution for only half of the problem: Elongating the I-beam until "mirroring" the cartridge/arm masses and lever lengths potentially aligns also the dynamic center of gravity into the vertical bearing axis. This reduces the dynamic, horizontally pulling forces on the bearing when the arm moves up and down with warps. Ie. it reduces a source of "microdynamically varying offset" with warps - and or vertical modulation...I have not seen a discussion of this aspect anywere yet, but it's a weak point IMO of the WTA and unipivot arms. If one considers the tiny metal point contact (rather a microscopically short metal string) of a unipivot this makes one scratch ones head, because this interface is "elastic by design" which "even" a ball bearing is, on a microscopic level.There is much talk about the elasticity of air bearings - but actually the "better" or more close toleranced ones are rather stiff (plus being chatter / variation free) compared to the situation in metal bearings, at least compared to unipivots.