The big question isn't so much if you're going to get a tm, but when to get one.
You need to have built a certain amount of volume and have the ambition to do more.
The trouble is you can't do more without the added productivity of a tm, which is what will pay for it, so there is a crossover point which requires either a leap of faith, or a decision to stick with what you have got. My first tm very nearly broke me, because I was in that no mans land, but luckily I got a national contract on the back of it at around the same time, so phew!
You also have to be totally committed to the project and let ambition drive you forward.
Is a tm for everyone, no.
Simon