The OP @cbl117 has stated,
" I've narrowed down to AMG and Brinkmann. I was able to audition an AMG Viella yesterday, and was looking to audition a Bardo or Taurus for comparison."
"How am I going to know what I want to purchase without demoing the options?"
The first statement is suggesting that it is known what is wanted to be purchased.
The differences between Brands is the drives are DD or BD.
The differences between the Models is that one is able to be configured to have a dual mounting for a Tonearm.
All the above models can receive a large selection of TA's or TA/Cart' configurations.
As the OP has not made it known about their intentions for the TA or Cart's to be used, the opportunity to learn how a assembly of ancillaries might best Wed to the TT's shortlisted.
If I were in the market to spend $15-$20K, I would be most interested in what I was going to be buying into, and especially how owners of the same or very similar describe their experience, if a report is offered. With this info at hand, the conversation one has about about their expectation for what is to be demo'd will be more sure footed and project a solid intention.
Not too many years ago I was introduced to and become very interested in a Bespoke Built Tonearm that has been produced in small numbers by a very adept EE with skills that are extended into micro engineering. To experience the Tonearm in use and compare it to my other owned TA's. Over the course of a year, I travelled a few journey's that are close to 200 miles as a round trip. The outcome being all roads lead to the purchase of this Bespoke Built TA, it has superseded in use all other owned TA's.
I learnt what I was buying into, and am also quite confident, I will have to find another £5K - £10K as a purchase price to supersede the selected TA. I can say this as it has made a TA that is very respected and retails at £3.5K seem quite low in quality as a performance.
The route to how the purchase is finalised would be the secondary consideration.