Thanks for sharing Tom! Interesting read.
Based on the temperature profile I've seen, HX machines also tend to have a temperature incline profile especially when pulling ristrettos - if inclining temperature is something of desire.
I had a detailed read on the paper yesterday. It was pretty all over the place to say the least - some part of the discussions don't quite agree with the data. The data itself doesn't show a consistent trend when using different beans. The taste test contradicts with the data completely. The only takeaway I could get away confidently are the methods that they're using, and that taste experience can't be quantified by hard data.
I was also expecting to see some temperature graphs for the three profiles - but they're not there (how do they know if they've executed the temp profile correctly and was not affected by flow/coffee?).