One thing that I'd like to add is that the job I was describing above is a real worst case scenario, certainly the most minging job I've ever had to do: a wool axminster in an indian restaurant, probably 7 years old, neglected in its first years of life and then being attempted to salvage after the damage has already been done.
It had been previously shrunk by another cleaner before I took over its care, and even with the TM we still had a couple of small shrinkage issues (shrinkage already pre-qualified with the restaurant owner, who was willing to accept it might happen and get a fitter in to sort it)
In this case, yes a TM definitely cleans better, hands down. There is no way even if I had doubled the time spent with a porty that the visual results could have been up to the same standard.
But in run of the mill domestic and light commercial work, on average the visual results of a TM don't really go too far over and above those I was used to getting with the porty, it's just a question of time effort and lots more puffing and panting. The crunch is that towards the end of a hard day's work it really is difficult to discipline yourself to take the same care as you were with the first few wand strokes of the day. That's the TM/porty difference.
But I have done jobs with the TM that I know wouldn't have ended up looking so good with the porty. For example, a couple of suites I've done in the last month and a lounge carpet which was absolutely trashed by kids (drinks, food etc). I've had to walk away from a flat-weave viscose suite after several fruitless hours with a portable, so frustrating but I just couldn't make any visual difference...... did a similar one with the TM & drimaster and it was just like wiping mud off a tiled floor, i think it was mostly the heat that made the difference.
With the porty, a dirty carpet/suite automatically calls for detergent in-tank and I know for a fact that this meant it wasn't left in an ideal condition. So yeah it can
look nice and clean but you're making a sacrifice, even with the best engineered chems there still must be some detriment to leaving detergent behind.
Waffling now, I'll stop