Craig - you can treat them once and for all, or you can carry on pecking at them forever, whilst they slowly eat the carpet away. It depends on the economics involved, I've done a couple of jobs recently where the customer didn't want to go the whole hog because the carpets weren't that valuable to them, so a "containment" measure was carried out at a much lower price. Horses for courses

Doug - My observation of the culture on this forum seems to be that the majority have tended to copy what a certain minority say. This sort of thing can perpetuate a completely misinformed point of view, unfortunately. You're a social outcast if you dare step away from the "general consensus", which is why most folks just drop into line and conform to fit in, whether they believe what they are saying or not.
Leaving names and suppliers to one side...
Switching over to a colloidal has been the biggest revolution in my cleaning for a long time. I don't know where people get this idea from that they're no good on synthetics. Personally I've been able to attain just as good results on a trashed rental polyprop as I could have done with a detergent, and I'm pretty sure that many others regularly using colloidals will say the same.
It just takes a little bit of adjustment and understanding of how the product works. It took me a good few months to get my head around it but now I wouldn't go back to using detergents as my standard approach.
I honestly don't think that the
visible results of cleaning with colloids are anything significantly over and above detergents, it's just the complete package - one product in one sprayer at one dilution rate for both carpets and upholstery, whether you're extracting of using a LM system. You've also got the advantage that you're not leaving any residues behind to cause resoiling, and you can even add a little more product on after cleaning to deal with things like dog or smoke smells.
Maybe it's not so big an advantage for truckmounters, perhaps colloidals make the biggest difference to portable users? Nothing to do with "how much dirt it gets out", but purely with the operational aspect. I've found that despite what may be claimed, you do have to use plenty of it and get quite heavy with the agitation in heavy soil situations; a much longer dwell increases the effect too.
This is fine for a portable setup, but a truckmounter who wants to rip through jobs as quickly as possible isn't maximising the investment he's made in his machine - he doesn't want to go round a whole house with a rotary and sit looking at his watch waiting to extract.
Not running a truckmount I couldn't really say if that's exactly the case or not. I'm sure if the area to be cleaned is big enough, the job could be worked in such a way as to incorporate using colloids like this, especially with a 2-man team. However, reading your proposal of how you're going to attack that carpet, it's pretty much the same as I'd do except you're using four products where I'd be using one! (disregarding spotters of course).