Blah, a correction
Sorry: "previously the power nozzle was the loudest part thing," should be "previously the power nozzle was the loudest part of the vacuum." I wrote that without checking the preview over again after doing some edits earlier.
As to agitation: If a X doesn't provide enough agitation, a Sebo Essential G or a 370 has manual adjustment, as do the the ET nozzles. You can set them all the way down. However in my experience of using the X4 using the green brushroll ("For delicate carpets." My X4 was second hand it came with the green brushroll.) alongside the C3.1 with the ET-1 (Has the normal blue brushroll) set to the lowest height and with the X4's automatic adjustment, I haven't had any issues pulling larger particulate out of some rugs. Abeit I think the X4 is a little more "grabby" than the ET-1 on a wand when it nails the height adjustment, it seems to want to pull forward with more force. The X4's head seems to vibrate carpet infront of it moreso than the ET-1 nozzle from my experience.
But I wouldn't go as far to claim that the Sebos would compete against some of the machines with the brushrolls with the beater elements molded into them or some of the uprights with really aggressive brushrolls. Like the Bissell Powerglide Lift Off that Roger has a video review on Youtube.