I think Dual Sanitronics are one of the nicer Kirbys in my humble opinion. I like that they don't have a transmission which is an extra thing that can break on a vacuum. I also like that the nozzle width is much smaller where it can actually clean carpets just slightly better. And I like that they're lighter as well. But even those I still wouldn't use for myself either.
And I still have to respectively disagree with you. If Kirbys were supposed to be the best vacuums on the planet and I'll admit there was one point when I really thought they were. Everybody would still keep their Kirby, Kirby wouldn't even have to sell vacuums at Costco today, and Kirby should've picked EVERYTHING off of not only my carpets but my grandparent's as well. Earlier this year we ripped out some carpets from my grandparent's house and the house always had a Kirby, especially the last 8 years when the Kirby took over the house as the main vacuum after the other vacuum had died. There was a BUNCH of sand, grit, and even cat litter left over from underneath the carpet. It's not even shag carpet. This backs up my one point and Performance Review's video of the Kirby which I don't think you've ever watched, Kirbys would've picked ALL of that up if it had more suction power but it doesn't. This is one of the cons of a direct air machine. Sure it may pick up more finer stuff like flour but even with more airflow, it still cannot pick up heavier dirt off the carpets. Actually there was also a time when we also had some of our carpets ripped out in my house, I vacuumed with a Kirby in my old bedroom where I used to do baking soda tests at with my other vacuums, there was even baking soda left underneath the carpet. And that was when I started having doubts on Kirby after being convinced that they were the best. Vaclab does all his testing at his house, I happened to clean other homes with different style carpeting, floors, and surfaces. So not everything he would conclude would be the same for every home. Also his testing is based on science. Performance Reviews' tests is based on what a consumer would normally do in a home. You're not gonna like to hear this but I actually agree with Performance Reviews more than I would with Vaclab. His points make more sense to me. I may not agree with him on everything but if I needed a opinion on a vacuum, I would honestly turn to him over Vaclab and even Vacuum Wars since I don't really agree with his videos either. At least though I'd rather hear from Vaclab than I would with Vacuum Facts, his videos are definitely more confusing than the others. Last but not least here, I've definitely had others issues with using direct air machines. As I said previously, they're just outdated machines. I'm tired of changing belts, they don't have good enough filtration to help with my allergies, they don't have attachments on-board and I do need to use the hose more often than yourself would, etc. I mean direct air machines are just simply not for everyone. With proper care yes they could last for a bit, in fact I take the best care on all my machines. But I generally find bypass machines to be the more reliable than direct air machines and this is coming from someone like me who was in the vacuum store industry like Performance Reviews.