I had the Triflex on loan for two weeks alongside the Dyson V15 I already owned. The first thing I noticed was the weight. At eight pounds it is genuinely a different kind of object than the V15, and after fifteen minutes of overhead work in the living room I could feel it in my shoulder. The second thing was the suction. On carpet, in max mode, it pulled up enough debris from a rug I had vacuumed the day before that I went back and ran the Dyson over the same patch out of curiosity. The Miele had won that round.
The self-cleaning floorhead is the design choice that makes the suction usable. The head pulls itself down to the floor as you push, which means full contact across the whole width of the brushroll without you having to lean on the handle. On a flat rug it works the way it's supposed to. On a transition between rug and hardwood it occasionally felt sticky and needed a small lift to clear. Auto floor-type detection adjusts the suction without you thinking about it, which is the kind of feature you appreciate by not noticing.
The dual battery setup is the headline argument for paying this much. Sixty minutes per battery, two batteries in the box, and they hot-swap without restarting the machine. I cleaned the whole house on a single set of swaps without thinking about charging. The materials feel like an appliance, not a gadget; the latches snap with the satisfying weight you'd expect from a brand that makes vacuum cleaners as appliances rather than tech.
The 3-in-1 convertible format is the part where I stopped recommending it to friends. The vacuum body can be reconfigured into three layouts (battery on top, battery at the bottom, handheld) and none of the three is better than a vacuum designed around one of them. The bottom-heavy layout is supposed to be the all-day workhorse and instead feels nose-heavy on rugs. The handheld is awkwardly large. The configurations take real force to lock and unlock, the kind where you double-check you haven't broken something. I converted it three times in two weeks and then left it in the upright position for the rest of the loan.
Maneuverability is the other weak point. The Triflex doesn't pivot the way a Dyson does, and pulling it backward across a rug noticeably loses suction. After the first day I caught myself making three pushes for every two I would have made on the V15.
The price is the hard part. At twelve hundred dollars the Triflex is more than twice a V15 Detect and more than triple a perfectly good Tineco. The build is genuinely better than either. Whether the build is worth the math is a question about your relationship with the Miele brand, not the vacuum.
Verdict: Buy this if your dishwasher and oven are already Miele and you'd rather everything in the house match. If you're shopping on what cleans best per dollar, get a Dyson V15 Detect.