] i may have missed it (i'm not good at watching videos lol) but did you spend the same amount of TIME climbing on the x20 as the hpr40? that will be the biggest factor by far, because the slower you go the higher the proportion of the work that you - the rider - are doing. if you're putting out 200 human watts and you climb for an hour, that's 200wh. if, because one bike is providing more assist than another, it only takes 45 minutes, now you're down to 150wh and the range is going to drop correspondingly.
incidentally, with me keeping my heart rate under 100bpm, and not pedaling very hard (150w ish) i got 3.9m/wh on a fairly controlled test a few days ago with the x20. average speed 16kph. the math tells me that i was pedaling at 225w (which is about what i did when not as worried about my heart) that number would go up to 4.8m/wh.
probably a bit lighter than you but also not pedaling nearly as hard, so the 3.9 vs 4.0 is a satisfyingly consistent result!