I've been cleaning one of these regularly ( 6 monthly, there are two small dogs ) for the past 5 years and started with HWE, went on to Von Schrader machine and then Dry Foam with Bonnet Mitts.
The last of these has proven to be far superior in terms of.............
* Standard of clean
* Lack of re soiling
* Time taken to complete the job
Some HWE diehards will suggest it's impossible to achieve as high a standard as they do, using this method and continue along their chosen path, just as some believe the Volvo Estate, or the Land Rover or Classic Martial Arts are unbeatable, while others have Tried and Tested and made informed decisions after comparing methods.
With HWE you could find delamination even without solvents and the tracks left by upholstery tools will need to be brushed out or towelled and you will also need to assist drying by towelling or use a blower.