@dover
If you adjust VTA on your Holbo whilst playing, the stylus position will move away from the tangent. This is basic geometry
I am with @hb22 on this one! The Holbo VTA adjustment raises or lowers the arm vertically, and if it is done to compensate for different record thicknesses, the tangent geometry is completely unaffected. If you check pictures of the Holbo you will see that the support rod the tonearm pivots around is pretty much in the plane of the record (cartridges do vary in height a bit). My description of the tonearm as a T is oversimplified - it is more like a + where the | sits over the - .
Now, trying to compare Eminent Technology tonearms (model?) with Holbo is interesting. If you sketched the architecture of each on a table napkin, you might think they were the same. The way I see it, the excellent reviews of both tonearms validate the architecture of each and highlight how much better they can be than conventional pivoting tonearms.
Properly adjusted pivoting tonearms have Horizontal Tracking Angle errors rising to 2-degrees at two points during playback. For stereo records, where each channel is cut at 45-degrees, HTA is just as important as VTA. Many audiophiles obsess about VTA but conveniently forget about HTA.
Despite the architectural similarities, the design details vary considerably between ET and Holbo. For example, the balance weight alone on an ET tonearm weighs about as much as the entire Holbo moving assembly. Remember, the total sliding mass is what the stylus has to pull sideways!
When Colin Chapman wanted to improve the trackability of his Lotus sports cars, he famously "added lightness".
The Holbo is fully integrated. When you push the button to start the platter spinning, the air pump automatically switches on. When you stop the platter, the air pump keeps going for a few minutes before automatically shutting down.
The tolerances on the Holbo air bearings are so tight, almost no air flow is needed. The air pump is very quiet to the point where I cannot hear it at all unless I press its box into my skull bones. Complaints in reviews of AT tonearms suggest its air pump is so noisy it needs to be in a separate cupboard, if not a separate room.
The Holbo does not have a detachable head shell so swapping cartridges will likely take 20 minutes or more. But for the price of a system with an AT tonearm, you could buy two Holbos!