Ian, this is an issue that gives me trouble all the time. Cleaning rugs I find that they all have to go through the process at least twice, sometimes up to 5 times. I built a beater bar grit remover that gets tons of dirt out after the first clean. Repeatedly vacuuming from the back can get enough grit out to fill the bag on my sebo. Some rugs the dirt never stops coming.
My CFR machine works a treat but I still wonder if even more power would help. 1000 PSI sounds like it should be more effective. The thing is, I believe that all cc machines are designed to clean to a pile depth of about 2-3mm. All the rugs I clean are much thicker than that. Even with 1000 psi I think that the pile of the rug baffles the flow of water enough to prevent effective soil removal more than 3 or 4mm. I'd love to crack the problem without the expense of the Behar System. Have you seen the Ausrailian system from the US? It uses a compressed air wand for dry removal, then the rug goes in a bath and the wand is used as a sort of Jacuzzi agitator
Anyone in the Milton Keynes area got a monster truck mount and want to come and do a couple of jobs for me? I'd like to see what they can do.