Alex,
I was around when the Turbopowers were factory fresh.
I started collecting brand new Hoover cleaners in 1983. My first cleaner was a Hoover Sensotronic Total System 5 purchased from Seeboard in East Grinstead, West Sussex. My Dad was kind enough to sign the hire purchase forms and I paid for it using my pocket money and any extras I got for doing odd jobs.
The second cleaner I bought from Currys in East Grinstead was my first Turbopower, the top of the range blue autoflex model and from then until the mid 90's I must have owned at least one model from every range. I did photograph most of them and some day I will put a slideshow up on my Youtube channel showing all the cleaners I owned.
I have one of the last Turbopower 1's that I've owned from new and I couldn't tell any difference between the plastic that model is made from and my very first Turbopower bought in 1983. If a Sebo X4 and Hoover Turbopower were dropped down the same flight of stairs, I am fairly certain which cleaner would come off worse, but there's no way I am going to do that test! I have a Sebo C1 and C3 Power Plus cylinders and they are certainly better built than any of the Hoover cylinders I had. The C series reminds me somewhat of the first generation of Sensotronics which for their time were pretty solid machines, but the plastic often made a creaking sound when they powered up and when they were turned off. My Sebos don't suffer from that problem, which I believe is down to better quality plastics and superior build quality.
The Turbopower 2 was certainly an improvement on the first generation certainly, but still not as well made as a Sebo. Again I had several Turbopower 2 cleaners from brand new, so I am making these judgements from my personal experience. I still have the base model Turbopower 2 that I've owned from new, so I can compare it directly with my new X5. The problem I have experienced with my Turbopower 2 is the belt stretching in a short space of time, resulting in the agitator not working efficiently. If Hoover were to reproduce the Turbopower 2 with a toothed lifetime belt, stair cleaning hose (like the Turbopower 3) and upgraded filtration, it would be a worthy contender to the Sebo Automatic X. The tool set up on the Turbo 2 and 3 is certainly better than the Sebo with its tendency to topple over unless you hold the handle or lay it on its back while using the extension hose. I don't rate the Sebo for above floor cleaning but it excels on my carpets and cleans consistently well for me.
Like I said in my previous post, I am not going to argue over a vacuum cleaner. All I can do is comment on my own personal experiences and allow others to form their own opinions based on their experiences. I can see why you like the Turbopowers and I can understand why you have formed your opinion on the Sebo, so let's just respect each other's views and try not to get into a slanging match over what most people would consider to be a very trivial subject. Again, I don't want to preach to anyone, if folk want to bitch and name call, let them, it can be quite entertaining sometimes, as long as I'm not in the middle of it ;-)