I used to only do T&M I thought it was the most fair way of charging.
These days I stay away from T&M because:
For starters you have guaranteed yourself of no real profit potential.
The homeowner (and even some GCs) rarley have a realistic idea of what it will cost.
Remodel projects ALWAYS cost more than they anticipated, causing the homeowner to get real touchy about every move you make, phone calls, bathroom , coffee, lunch, etc. Even how long you take to wire something!
I had one T&M job I quit the first day because I ran to get parts and went through the Burger King drive up on that run, the homeowner quizzed me on how long I was at the drive up. I knew it would get worse the more she went over budget.
When your deep into the project and they are way over budget it's is all your fault! (So they think!) Even more so if they had been told a "ball park" amount, and you've exceeded it. You must be taking advantage of them! The next thing is they want a complete detail of every move you made and every wirenut used. One guy wanted us to start punching a time clock!!
In the end they want to negotiate your payment.
Not to exceed is not for me......why would I risk loosing $$$ and at the same time assure myself of NO PROFIT potential.
Just my experiences
Rick