BW's can be wet cleaned.........with care!!!!
Pre-vac really well (not a quick run over) pre-spray (but not to excess) with a M/S, loads of agitation and extract with minimal moisture and lots of dry passes. Also use drier's.
Not shrunk one yet.
If you spray with M/S is there less chance of them shrinking?
I would use Ultrapac renovate with it been a Polyprop face fibre.
Wayne you can always tack the carpet to either wood floor or gripper every foot or so leaving the head proud so the customer can remove when fully dry. Only takes 20 mins or so for a medium size room (add £20) to the bill, just gives you that little extra confidence, ive cleaned 100's and never had a complaint.
If your ever out on a quote and your not sure what to say/do just ring me, could have saved you £100 there mate

Mark