I will confess Richard that I've not tried the Duo P from Sebo, yet, so I can't honestly say if it's good or bad. Although, knowing Sebo, it won't be bad.
What I can say is that the Sebo's are superb machines as I use one and a lot of friends and family have one as well now because I think so highly of them. They are superb cleaners that just work and keep on doing so and are worth the money IMO.
But it is my own personal experience from using Bissell's, Vax machines and a few others that nothing can top the professional carpet boys, by a country mile. The machines that they use are way, way beyond what anyone would even consider remotely reasonable for domestic use and they remove a lot of stains and dirt.
If there's a "Magna Dry" I think it is franchise nearby they're well worth a try and really not that expensive. Certainly a lot
less expensive than a new carpet or often a cheap 3-in-1 thing that really doesn't even come close the the performance that the pros get.
And, they'll do more than twice the area in half the time.