Quote: “I’m a new RME customer. I have a nice Fireface + Quadmic + ARC rig and I’m happy with it.”
Congratulations on your equipment choice and welcome to the RME family where I am sure you receive excellent advice and assistance from expert voices, such as those who have been so helpful to me.
Quote: “When I'm working in Ableton in full screen mode, I cannot open TotalMix in an efficient way, as it switches me back to desktop. It would be ideal if TM could open up just like a plugin inside the DAW screen, without having to go to the desktop.”
With all due respect, the notion you request is in reality, not the ideal solution that one might imagine.
The best solution I have found is to have two large monitors and use one monitor for the sequencer, and the other for TotalMixFX and the mixer from the sequencer.
Today, large monitors can be purchased relatively cheaply and because this solution provides great convenience and a huge amount of time and bother saved, it is well worth the cost of the outlay.
This method has worked well for me, and all the professional users I have encountered, such that I regard this method of working to be a standard operating procedure for producers, engineers and serious home recordists alike.
Here’s a couple of “behind the scenes” movies made by family friends of Christmas recordings made for Charitable purposes, raising money for water projects in Africa. (They raised £50,000 on just the first one).
If you view the movies carefully you, will soon note the simultaneous use of two monitors, each dedicated to a specific task, which greatly improves workflow, making all necessary information continually available to the user.
The gentleman making the recordings and overdubbing has recently been made a Fellow of SMPTE, (The Society of Motion Picture and Television Engineers) for outstanding contributions to broadcasting technology which I’m very pleased about.
Long story short, in my humble opinion, you won’t find a better approach.
https://www.youtube.com/watch?v=ZAfp3FZWyqE
https://www.youtube.com/watch?v=Tj-0jI9_i9o