SUT Advice - Which Ones Are The Best?

I am currently in research mode.  I want to add a SUT to my set-up but I am finding that there is not a lot of information from my local audio shop resources.  It seems that SUTs are outliers in the high end audio world.  
That said, I have read several articles in magazines and the web touting their merits.
Of all the brands out there I am most familiar with Bob's Devices.  Art Dudley wrote many good things about his experiences with Bob's SUTs, and I happen to trust Art (God rest his soul), but I'm wondering if there are others I should consider as well.  Please post your recommendations if you have experience with any SUTs, regardless of brand.
As for my set-up, I have a SME 20/2 turntable, Tri-Planer tone arm, Lyra Kleos cartridge, and KTE LCR Mk5 Phono preamp.  I do not know if I will always use a Kleos cartridge but I do think I will always buy low output MC carts.  I hope to buy something that will work with low output MCs but have some adjustability just in case.
I'd love to hear your recommendations.
I got my 1st MC cartridge not long ago, and after research and advice here, went with this one:

they are getting expensive, and harder to find

a. PASS lets you use it for a MM or MC High Output thru it, bypassing the transformer

b. 3 inputs, front selectable, then off to a single MM Input.

c. 4 optional x-factors/impedance loads, for my first, and future MC cartridges
(front switchable, not rear or internal dip switch changes).

This model, FRT-5, has 3 inputs, PASS, and it’s Transformer is designed for MC cartridges in a range of 3 to 10 ohms


Entre ET-100; 3 inputs, PASS, 3 Optional Loads, front switch


Denon, 2 inputs, PASS, 2 optional loads
not snark, but in my experience more than a few audiophiles don't much care about phase. I do.

nice to have Jonathan weigh in.

@pindac there is a lot of wisdom in your post re; system matching and synergy 

best to all, excellent thread
JCarr, thank you for the erudite post. For most of us, the needed gain is easily estimated, and the internal impedance of the cartridge is available from the maker, but I know of no instance where the primary inductance of the SUT is accessible to the end user. How does one acquire that data point?