Eminent technology et2 on Linn Lp12

@ct0517 The fact that you may not like the idea of mounting an arm that needed constant tweaking and maintenance doesn’t NOT make it tried and true! This combo was utilized extensively back when the ET2 arm was popular, and as I stated...it worked well from a SQ perspective. That fact makes it tried and true.
The OP asked about what people thought about the combo...clearly someone had told him that the combo could work...and so he wanted feedback on it.
You ask what were the mounting options....if I remember correctly all of the arms were mounted such that the base was at the rear of the arm board and the arm(bearing rail) extended across the back of the table...not in the traditional manner, wherein the arm extended towards the front ( although in this way, the actual arm of the ET2 did extend towards the front of the table....like all other arm mounts.). This arrangement allowed the arm to transverse across the platter from the right to the left...and it worked well.

Since you don’t own a Linn, can we come to the conclusion that you actually have very minimal experience with it and are just here conjecturing opinions, based on no real understanding or experience!

When you thinks of an ET arm you immediately think of a non-suspended table, but on reflection, I remember hearing and seeing a lot of Oracle owners using the ET arm on their 3-pillar suspended tables, therefore, why not a Linn.  My questions to the OP, why the ET when there are a number of well regarded arms (simpler and less finicky) that work very well with the LP12.

Pkvintage

If someone handed me an LP12 today and said put an ET2 on it, this is what I would do first as a test - and it doesn't take a lot of effort. This is a quick 5 minute analysis - excuse any grammar, etc...
 
1) Level the LP12 plinth/platter without any tonearm.

2) Place the ET2 mounting plate over the existing tonearm hole. Establish height - use a holed wood shim if extra height is needed.

3) Acquire from the bolts place/home depot ; a longer bolt, nut, washer, and also a larger diameter flat stainless steel washer.
The Flat washer should be big enough to cover the existing hole from underneath.

4)Place the ET2 mounting plate over the hole. Insert the longer bolt down through the mounting plate and fasten it from underneath with the flat washer and nut. Level the mounting plate with its spikes. The tonearm is ready to be mounted.
 
5)Mount the ET2 tonearm and measure (A) how far off the plinth has moved from previous level if at all.

6)Re-level the plinth if needed, turn on the air and level the tonearm using only the air bearing (no movement) as a level. Not a bubble level.

7)Place the tonearm air bearing spindle at what is the beginning of the record position. (B) Measure the level at this position.
 
8) Move the air bearing spindle to the end of the record position. (C) Measure the Level again at this position.

This has me curious, so I am interested in your measurement findings at - A - B - C, to find out if the air bearing spindle's weight, as it traverses across produces any deflection. Either here, or on the ET2 owners thread.

Cheers

@testpilot  Your point about a number of arms working well with the Linn isn't actually correct. Unfortunately the opposite is more accurate..there are few arms that work well with the Linn! The Linn suspension requires an arm that is not only light weight, but also has the wiring to it in such a fashion as that it cannot impact the suspension. Many a great arm won't actually work on the Linn..
The OP happened to ask about an arm ( the ET2) that can work on the table, although I think there are better alternatives available today. 
As a 'Linnie', it is my biggest complaint to Linn, that the actual arms that are supplied and available that work with the table...are in fact far less able than the table itself!
IMHO, the basic platform deserves a much better option than the Ekos SE-1, as an example.