Hi Matt!
I might not be able to solve all your thoughts or problems with the Model 24, but I will share some of my way of using it.
I guess my workflow is quite "simple" in comparing of how others would use it. First of all, I'm an "Old School Guy"... (65 years this august)... meaning I'm old enough to have used the Tascam Portasrudio 244 back in the middle of the 80' (which I still own... bought in 1986 and still works like a charm). Also I play mostly guitar, bassguitar, harmonica and are "cheating" on keyboards every know and then. Since what I am mostly recording are "Classic Rock, Bluesrock, Boogierock, Southern Rock, Jazz, Soul, Gospel and Country. I am not in need of most of more "modern" or "extreme"ways of using hardware and software together. But I DO use loops every now and then just to spice up my recordings.
So... this is how I often use my Model 24:
First I compose a "preliminary" drum track in Superior Drummer 3 that follows most of how my song is arranged, and then convert the midi to a wav-file. Then I also compose a "preliminary" Keyboard track in EZkeys using a combination of midi and my own "analog" playing to go along with the drums, and then I convert them also to wav-files... all inside Presonus Studio One. Then I route those tracks/wav-files the right way out to Model 24. Usually recording them on stereo tracks 17/18 & 19/20 respectively.
And now the really FUN starts!
Now I can use the Model 24 as a place to practice & record guitar, bass, harmonica, singing or anything that uses a microphone, amps etc without even have the computer connected. I lay down different instruments on different channels, testing different ideas, overdubs and whatever I want to use with the drums and keyboard as a "backing track" for building up the song. This is actually the real reason for me wanting to use an "outboard" mixer/recorder like Model 24. I want the "freedom" to skip the "harassment" of a computer when I want to be musically creative. No "computer startup time" and other "computer related" glitches and hiccups... just to plug in and PLAY when inspiration hits you. Model 24 works much like an old "tape-machine" or Porta Studio 244 ... just "plug & play"!
When I am satisfied with the result I simply transfer/record all channels on the model 24 to their respectively channel in my Daw. But I do NOT transferring the 2 channel main mix tracks on channels 22-24 since I have no use of them since I will do the real mixdown later in my DAW.
(OR maybe I will route everything back to model 24 for final mixdown/mastering there when the song in my DAW is finished... just to get some (I suppose) imagined "analogue warmth feeling" added before or during final mastering)
Back in my DAW I now have the original drum & keyboard midi-files still present in my song project, alongside everything I have recorded on the Model 24. For example: On mono channels 1-12 I have the recordings that I have done on Model 24. Stereo channel 17/18 have my drums as midi-files available for more fine tuning of the drums in Superior 3. And on stereo channel 19/20 I have my keyboard midi-files also ready for more fine tuning in EZkeys. Stereo channels 13/14 & 15/16 & 21/22 (the Bluetooth channel) are still empty and ready for further use with other digital instruments.
After this I start mixing in Studio One and make use of different vst's, compressors, reverbs, delays, limiters etc. I may use a bit of Melodyne to correct small singing mistakes here and there just to polish things up. Maybe record some backup vocals, maracas etc on the still not in use channels etc.
To sum it up:
1.Creating a "backing track"(drums/keyboards) in my DAW.
2.Transfer/recording the waw-files to Model 24
3.Rehearsing and recording the "analog" REAL

instruments for the song.
4.Transer all channels exept "MainMix" 22/24 back to DAW.
5.Finetuning/arranging my midi drums and keyboards in Superior Drummer & EZkeys.
6.If neccessery record my own "real" keyboard.
7.Adding effects & Mixing/Mastering inPresonus Studio One Daw.
8.(task in progress)By Presonus Faderport 8 & 16 for better workflow in DAW.
About "Daw-controller issues": Only Model 12 have those in this Tascam series, but I find them quite limited compared to a dedicated Daw-controller. Personally I don't mind "mixing in the box" altough only a mouse and keyboard commands can be a little tedious from time to time, so I am thinking of buying a dedicated daw-controller soon. And my choice there is between Presonus Faderport V2 which only can control 1 channel at the time which is ok but a bit tedious that too, so I'm probably will go with Presonus Faderport 8 or 16. Since I work in Presonus Studio One these daw-controllers are especially good together with Presonus own products compare with Behringer etc
About stability issues. Well, the only thing that has happened to me is that if I forget to have the same sound resolution in both DAW and on Model 24, it will complain about "USB mismatch"

... but that is quickly addressed by adjusting my settings. To me it is very stable and is built with quality... it's sturdy, robust... the knobs and faders are robust and professional, and it LOOKS SO FREAKING FREKKING GOOD TOO! The most beautiful furniture in my apartment!



Hope some of this may be of help in your thinking!