As someone that is primarily concerned with process efficiency (and especially process simplicity) here's why I was always turned off by arroyo's patent method:
It basically plays with fire. When you are basing your method on using fractions 2, 3,4, 6, and 8 (that's probably wrong, just used as an illustrative example) you open up your product to variation via human error. As we all know volatilities of organics change depending on the relative composition of the complex mixture. It's well and good to say "well, Raffie Arroyo did it, so can you all" but expecting to not make cut point errors in such a complex cutting scenario is unrealistic at a production scale. I'm sure the birectifier provides insight into that, but I have to ask... is it valid information if your production scale equipment doesn't have exactly the same capabilities?
Maybe Arroyo had the infrastructural resources to conduct his method flawlessly. Maybe he didn't and the patent was a panacea to enfranchise his company's lawyers to sue competitors that had a similar flavor profile to theirs. Who knows.
All I know is that understanding the process of how esters are formed in the still from constituent products that result from fermentative biology (and conversely how they break apart via hydrolysys when the concentration of alcohol is reduced during proofing) is essential to understanding how the flavors in great rums are created. Strong acids, alcohols interacting with carboxylic acids and long durations of reflux are how these esters are created... and whether or not you have a birectifier doesn't really enable you nor does it prevent you from making these flavors present in your finished product. I must say that I'm very motivated by @bostonapothecary's body of work and it made a huge impact on my development as a distiller. Thank you sir!
I'm reminded of 'lost spirits' and how they said they could make 30 year rum in 30 minutes, but couldn't present a rum under 120 proof that had a heavy ester load. That's because they were trying to sell 'accelerated aging' licenses to their so-called 'proprietary technology' which was really just a combination of a hot-process oak product extraction vessel and a large lab still that didn't do a great job of fischer esterification. They were banking on people that didn't take an o-chem class being willing to spend a lot of money on some magical way to print money. Speaking from experience... anyone interested in these topics should download some lab procedures for fischer esterification and do the work. You'll learn a lot.