Firstly, hello and welcome.
Secondly, I disagree with you MASSIVELY. I've been using Sebo vacuums now for at least 5 years and most of my relatives now own their machines. I've never found the suction to be a problem and in my experience of the D4, the suction is very similar to that of a Numatic Henry. I'm sure one of our other members will be able to give you some technical data regarding airwatts compared with other cylinders on the market.
Thirdly, no straight suction cleaner will ever be able to deep clean a thick pile carpet.
Of all the issues I know of people having with their Sebo's, the suction has never been one of them. The most common issues are dislike of the automatic height adjustment (which is more of a personal preference thing) and the X series falling over when using the hose, which I agree is quite annoying.
