If I understood all that, then Sound Blaster + MT-32 is how DOTT is meant to be played, and the CM-32L effect support is just there as a fallback for those who didn't have a Sound Blaster, or alternatively for those who want to make their CM-32L's play the fallback sounds anyway so they can feel special. I'd put it in a separate category from Might and Magic III, Ultima Underworld, and even LSL5, which really do need a CM-32L for the complete experience.
Depends on what "you" consider an "authentic" or "optimized" or "meant to be played" experience.
If you have the floppy version, but without the Roland (and GM) upgrade, is it "meant to be played" with SB/Adlib music? or also with SB FX?
If you have the floppy version, but with the Roland upgrade, is it "meant to be played" with Roland music? MT-32? or LAPC-I/CM32L? GM? With or without SB FX? MT32 with SB FX? CM32l/LAPC-I without SB FX?
And then theres the CD-ROM version with all the voice. Same questions apply.
If it was composed on a Roland SC 55 (3 different composers mind you), it would seem that GM would be preferred, especially for the floppy version or without a SB. But if configured for Roland with a CM32L/LAPC-I..you get those extra FX that you dont get with GM or MT-32.
Did i mention the "it doesnt sound right because that isnt how I remember it" bias preference? For many, that factors heavily - others, not so much. Some people are ok with using any of the hardware that was available at the time, even if it wasn't anything they owned or could afford at that time for a "meant to be played" experience, and so on. Some think any modern hardware/software that works with the game is "meant to be played"...
Corrected drivers that allow combinations of audio devices that werent allowed or were limited then? is that "meant to be played"?
You get the picture..."meant to be played" is very subjective in the ear of the beholder in the final analysis...
Whether or not anyone "feels special" or not..well...gaming is some part an emotional experience...experiencing a game multiple ways or having an "optimal audio experience" may be what some are going for.
I wouldn't put it in a separate category at all. The game makes use of and outputs extra soundFX on a LAPC-I/CM32L (especially meaningful on the floppy version which has little to no SB FX). That can't be denied. Whether or not "you" experience it depends on your game version/configuration/hardware/updates, or, if you care, as always.
I think the situation is similar with Beneath a Steel Sky's floppy version. Referencing a video by PhilsComputerLab, the crusher at the very first interactive room makes a constant "CLANG" sound. In DOSBox, you get a different sound depending on whether the game is configured to use Sound Blaster or Roland LA, and the Roland mode has different sound effects for MT-32 and CM-32L, giving three CLANG effects in total. But in ScummVM, the sound driver selection only affects the music, and sound effects are always the Sound Blaster version.
Again, utterly not uncommon to have multiple versions of the same soundFX depending on the game version/hardware/updates/configuration. Par the gaming course in this era.
SCUMMVM has plenty of limitations and drawbacks (in addition to some useful functionality) as noted here and elsewhere. To my mind the limitations outweigh the benefits, but I use it for testing purposes etc. Their focus is on adding more and more games and "improved and corrected gameplay" -providing maximized original experience accuracy seems very low on their priority list. The audio infrastructrure and development is exceedingly poor, especially in terms of replicating the original audio options and configurability which then directly affects the output.
Think about it. SCUMMVM has been around for, oh, nearly 15 years, and they are just now getting around to perhaps even correctly detecting the CM32L ROMs and pondering that their audio infrastructure is insufficient to say the least in terms of full original replication, but now they even rolled back that recent change because golly their SHA1 ROM-verifying code might be infringing in some way? Again, they just aren't interested enough in accurate original audio replication (amongst other original game aspect replications) and never have been.
DOSBox provides all the tools and configurability flexibility (along with other tools such as MUNT) to really allow anyone to fully experience ALL the different hardware configuration modes (and experience differences thereof) of these games, as originally intended, and, otherwise.
This is just one tiny example, but its the same theme time and again between SCUMMVM and DOSBox.
Regarding DOTT and Sound Blaster + MT-32, wouldn't modern ScummVM be fine? The only limitation I'm seeing here is that there's no way to turn off Sound Blaster support (that I know of), which I think is only an issue if you really want to use your CM-32L as a Sound Blaster substitute.
See Above. Depends on what you mean by "fine" - totally subjective.
I would not suggest that the LAPC-I/CM32L/etc (or even the MT32 in special reprogammability mode) are "sound blaster substitutes" but rather have additional capabilities which may be exploited by some games, and some games better than others, to provide non-musical soundFX. In regards to DOTT, in some cases, these additional soundFX are superceded by the SB compatible digital versions.
I have not gone through the entire game to see if there are CM32L/LAPC-I specific soundFX which are NOT superceded by SB digital versions - perhaps someone else has. If there are, or if you want to experience the CM32L/LAPC-I effects, SCUMMVM cannot replicate that.
Consider the issue of the floppy version, with the Roland upgrade and SCUMMVM - the SB digital soundFX override the CM32L/etc ones, but effectively only in the intro. Later on in the game when there are no SB digital soundFX to override the CM32L etc ones, no special CM32L/etc soundFX can be heard, because SCUMMVM completely lacks any support for them in the first place.
This is true of all other games that have specialized LAPC-I/CM32L soundFX and SCUMMVM as well - try listening to Lure of the Temptress in SCUMMVM (no matter whether you use the internal or an external MT-32 device with the CM32L ROMs etc) versus in DOXBox, either with a real CM32L/etc or with MUNT (internal or external again) configured with the CM32L ROMs - it is literally night and day, or, perhaps ...something... and thunder...you'll hear. You'll never hear the stunning usage of the LAPC-I/CM32L soundFX in Lure on SCUMMVM, because it completely lacks support.
Ultimately, its up to you and your preferences - I happen to prefer greater accuracy, configurabilty, and flexibility so that I can experience these games maximally. Other than testing, I avoid SCUMMVM.