My fuel usage on my tm works out at 8% which i think is quite reasonable. I had to clean a suite yesterday using my portable, and after using a tm, it just aint the same. If there is evidence that there are tm's working your area, some would say if you can't beat them, join them.
If a tm is regularly serviced, and i do my own servicing as i trained as a mechanic, they will last for years. I paid nearly £9000 for mine, and i expect it to last a minimum of five years, so it is not that expensive. There are tm's out there that have run up 8000 - 9000 hours so they have got theier moneys worth.
Lets look at the likes of Chem dry. They market aggressively and have built up a good business of insurance work, but as somebody has said, they might be slowing down in the domestic sector because people are looking for a good deal. now as it turns out, Chem dry are now marketing their own truck mount. Why? Because they like everybody else needs to have an edge over their competitors.
I'm not starting a my machine is better than yours arguement, but i believe a tm will out perform a portable, as i have both. You need a unique selling point that the competitor does not.
Dave