I think the time savings with a TM are minimum. You still have to pre-spray, agitate, move furniture etc some people even vaccum!!
Rinsing with a powerful porty doesn't take that long as it doesn't take that long with a TM.
The two benefits i see with a TM are
a) the not having to fill and empty. But does this really save enough time to add an extra couple or more jobs on a day??
b) a marketing thing. i.e. mines is bigger than yours! lol Granted a TM is a great marketing tool.
Personally I think people that went from porty to TM and think there was a HUGE time saving where just too slow and disorginised with thier porty
