Harvey, I'm curious to know why you view upholstery as so risky and fraught with danger! There's just as much can go wrong with carpets, it's all down to experience and confidence.
Subject to pre-testing (which will gradually become superseded by your experience) you can clean just about ANY modern upholstery fabric with a water-based system. It's pretty resilient stuff, it has to be otherwise furniture wouldn't be covered in it!
Of course there are exceptions, but the problem is that you've maybe been listening too much to the scaremainering marketing tactics of the manufacturers who sell "dry" systems.
The last time I dry-cleaned a suite because I didn't want to get it wet was about 3 years ago, and even then 50% of the reason for doing that was that it wasn't visibly soiled. If it had been dirty I'd have qualified with the client and extracted it.
I think the most common pitfall in upholstery cleaning is overwetting, so if you work with that in mind you've chopped out a huge part of the risk already.
Viscose is still fairly commonly found, although I've noticed recently that polyester is being used to replace the velour textures traditionally achieved with viscose in some fabrics. Marks & sparks suites are a good example of this.
Viscose is normally used to create the textured, pile part of a fabric, typically 20% - 40% of the make-up of the fabric. I don't think I've ever cleaned a 100% viscose suite, only a very old footstool from out of an insurance job which was the first time I learned about the "drowned rat effect"
That's one of two two things to watch out for with viscose - the matted down appearance it can be left with when water-cleaned, and also its loss of strength when wet. I've found that modern viscose, when only very short pile (up to a couple of millimetres), suffers no matting down at all after water-based cleaning followed by a brisk drying off with a fan and a gentle towelling off to fluff the pile back up.
You should be looking towards building your suite cleaning up to £120 plus for an average suite, as your experience and confidence grows. It's a lot easier to add on protector too, as many are protected originally. One of the first questions I ask when quoting is "Was the suite supplied with a protector on it?". This helps to plant the seed in the customer's mind that protector is important.
I sometimes under-price the protector and over-price the cleaning, so it all adds up to roughly the same but makes buying the protector a no-brainer for them
Lose the Fear