No, SCC-1 was a General MIDI/GS compliant sound card (part of the Roland Sound Canvas family), not a true MT-32 compatible. You are thinking of LAPC-1, which was basically a Roland CM-32L on a ISA card. SCC-1 was basically a Roland SC-55 MIDI synth on a ISA-card.

Roland SCC-1 used to be one of the better General MIDI sound cards you could buy at the time. Nowadays you can get even better General MIDI/GS music from DOS(Box)-games by using replacement General MIDI soundfonts with e.g. VirtualMIDISynth, soundfonts like Timbres of Heaven, Chorium Rev.A etc.

Roland SCC-1 did have a specific "MT-32 compatible mode" (enabled with a certain MIDI message) where it used a set of instruments that were in the same order as the default MT-32 instruments. This worked ok for those MT-32 games which used only the default MT-32 instruments and didn't change any default settings, but otherwise it would be more or less inaccurate. I think some other General MIDI sound cards had a similar, partial, MT-32 compatibility mode (e.g. the Waveblaster daughtercard?). In those MT-32 default games the SCC-1 could sound even better than a real MT-32, as its MT-32 compliant instruments were of higher quality than the originals. For instance, the Wing Commander and Elite Frontier music sounds better on SCC-1 than they do on a real MT-32 (but e.g. the Wing Commander sound effects sound wrong on the SCC-1).

Roland (more or less) MT-32 compatible LA-synthesis synthesizers:
- Roland MT-32
- Roland CM-32L
- Roland LAPC-1 (an ISA-card (CM-32L on a card), including the MPU-401 MIDI interface)
- Roland MT-100
- and some others I don't remember

Roland Sound Canvas (General MIDI, and the Roland-specific GS extensions on top of vanilla General MIDI):
- SC-55
- SCC-1 (SC-55 on a ISA-card, including the MPU-401 MIDI interface)
- and many many others

Yeah, if you are into using the original Roland sound devices, you should invest on the external MIDI modules (like MT-32, CM-32L; or in case of General MIDI/GS, Roland SC-55). You can use those external MIDI modules even with modern PCs and laptops, as long as you have a proper USB <=> MIDI adapter.

I haven't been able to use my Roland SCC-1 ISA card for ages, but then I don't care anymore. For me:

MT-32 music: Munt-emulator (I choose to use CM-32L ROMs with it)

General MIDI/GS music: VirtualMIDISynth with either Chorium Rev.A or Timbres of Heaven soundfont (Timbres of Heaven has the best instument quality, but I feel Chorium still gives better results with some games, and is generally closer to how Roland Sound Canvas sounded (instrument balance etc.)).

Depends on the game. With many (older) games you couldn't choose a sound card separately for music and sound effects, If you select Roland MT-32, it will play everything (also sound effects) through it. E.g. Monkey Island 1-2, and most Dynamix games.

With Ultima Underworld, you can select a music sound card, and then a separate sound card for speech (e.g. Soundblaster). Then e.g. the digitized intro speech will be played through the Soundblaster DAC, but all the sound effects are played through the music card, e.g. Roland MT-32/CM-32L, or the Soundblaster FM-synthesizer (no digitized sound effects in either case).

I think Ultima 7 was similar, having a DAC-capable sound card (like Soundblaster) would merely give you digitized speech in certain places, but all the sound effects would still be produced by the "music card", no realistic sampled sound effects.

It didn't have the LCD display that MT-32 had, and less other control knobs too I think. Merely just the on/off button, a volume knob, and audio and MIDI ports at the back.

Internally though, it had the same extra sound effects etc. that LAPC-1 had, over the vanilla MT-32 instruments. Some later PC games even used those extra features of CM-32L/LAPC-1, meaning with a MT-32 you might miss certain sound effects or instruments in the music, or some would sound wrong. Ultima Underworld is one of those games, the swimming sound effect.

With early MT-32 games (e.g. older Sierra and Dynamix games) it was the opposite, they were optimized for MT-32 and you might occasionally get incorrect sounds on CM-32L and LAPC-1. Cow sound effects in Heart of China is one example.

However, I generally found those differences minor, so I don't see that much point fret about using the CM-32L with MT-32 games, and vice versa. Close enough.

Doesn't sound like what? Those comparison recordings on that page sound pretty accurate to me. Which of the Munt recordings sound poor to you (compared to the corresponding MT-32 recording) on that page? I quickly tried out e.g. the Quest for Glory 2 Munt vs. MT-32 recordings on that page, and frankly I couldn't tell the difference. They sounded pretty much 1:1 to me. If there were some differences, I was unable to discern them (or then I didn't listed all the way through).

EDIT: Wait, in the "Conquest of Camelot" music I can tell maybe slight differences when I kept listening to them repeatedly one after another... but to me the differences didn't sound that major. Not sure though from which Munt version those were recorded. So maybe Munt is merely 99% accurate to the real thing at this point. Close enough to me, especially as Munt doesn't have those "glitch features" that my real CM-32L has with a couple of games (like that darn crackling fireworks sound in the Wing Commander intro, or crackling Inferno music).