I used to be satisfied with my portys - I'd upgrade every 3 or 4 years, and ended up with a twin vac, auto fill with metering, apo, sign-written with my decals, and I did good work.
We went TM when my son joined the business, meaning we had to do more work per week, and I was getting fed up with the thought that we weren't offering the very best service possible.
Now the water is piping hot almost from the start, without using the custy's hot water, or electricity, the items are left much drier, and the whole set-up is so impressive that a porty user coming after us is going to look like a DIY'er.
We set up quicker, move the wand faster and have less down time.
So, why not a TM? Not busy enough, scared of maintenance or lack of experience of a decent TM.
Why not a £3k TM? Maybe it sounds too good to be true, maybe, like us, if you take the step up you want to go the whole hog & get a new one.