I'm on my third. The vehicle has a mild steel one on when I got it, I fitted a second system, and finally replaced it with one of their stainless systems a couple of years ago now. Wish I had bit the bullet sooner.
The mild steel systems (they try and big them up as 'aluminised steel' which just means a silicone enamel high temp paint...) are expensive for what they are in my opinion, but most of the cost seems to be in the (labour intensive) downpipe section which is made from lots of little bits welded together. The rear sections including the tailpipe aren't too pricey. I wasn't too impressed with how quick they fell apart, but the vehicle gets used a lot and rarely washed...
I do, however, like the design and the fact they are local to me and I can get bits off the shelf. It's a decent bore, is mounted largely well up out of harms way and doesn't sound like a chav's Corsa like many systems (usually people just cobble something together and don't bother with a silencer because 'the turbo silences it'... no thanks!). The fit of mine have all been good. It is tight where it goes over the gearbox mount but the olive/air ministry style joints make it so easy to adjust and get it to sit just where you want and avoid rattling.
Very happy with my stainless one now. I agree about the hangers, they rust away for fun so I usually have a couple on the shelf. A couple I have replaced with cheap U clamps or similar as they last a lot longer and are far cheaper. The only other thing is the usual bug bear with stainless systems - mild steel flanges! The pipe itself is a good grade and is still very shiny under all the grime - in contrast the 'stainless' Double S system on the Carawagon looks like a 30 year old mild steel... awful.
So in general, the design is good, the fit is good. But they are pricey (especially the mild steel one IMO). I'd definitely buy another.
Oh, mine is a Disco 200 in a S3 by the way.