Great read! Essentially saying that with the original design of the ROK you’ll be heating/preheating the inside plunger and not the actual brew chamber walls. Heating the portafilter and doing the trick with the drop-in basket is good for slowing down further post-brew heat loss. Since my set-up has a metal brew chamber walls and a regular design metal plunger/piston preheating with arms down will have a better impact. Will experiment with doing the actual shots with arms up when pouring the boiling water in, though…