Kind of absurd for me to be having a conversation with myself like this, but at this point I'm simply documenting some observations for the sake of anyone else who might come along in the future in a similar situation, with similar questions and similar requirements.
Again, this is focused on the music creator who wants to work in a modern (circa 2020) production environment, with current 64-bit host, DAW, current hardware, and all that. The main question is, "SC-D70 or Sound Canvas VA?"
1) If you are working in macOS, with either a real Mac or a hackintosh, easy--go with the VA. Why? Well, unless you virtualize from within macOS, there's simply no official software/driver support in the now 64-bit only world of Catalina. I cannot confirm whether there are ways to get audio through ASIO with the SC-D70, but if you want to do any kind of patch editing or other advanced MIDI manipulation, you'll need a way to send those messages yourself. My primary DAW is REAPER, and while there are definitely ways to easily send commands using reaMIDIcontrol, and even do more advanced things like conceivably building a full control panel in JSFX, this headache is going to be on you. In contrast, SC-VA offers VERY good similarity in sound quality, provides access to all the edit parameters that are available via SC-55/88 generation hardware or GSAE software, and can also overcome its 16-part limitation through the use of multiple instances...
2) ...and it is here that I will touch on possibly the biggest annoyance of Sound Canvas VA but also note a very important distinction between the macOS and Windows versions: the Mac version loads multiple instances much more quickly than the Windows version. Prior to purchasing the VA, I had read in several places that there was an irritatingly long load time, almost certainly due to the software's copyright protection (since the trial/unactivated version loads with very little delay). I discovered that while the delay on my Windows machine (i7-4790k/32GB/SATA SSD) is for real, the same license on my 2012 MBP (i7-3615QM/16GB/SATA RAID-0 SSD) loads almost as quickly as the trial version did. Here are my load times in REAPER, for a simple project containing 1-4 instances of SC-VA and 16 MIDI send tracks per instance of the VA:
-Windows 10, one VA instance: 6-7 seconds
-Windows 10, four VA instances: 32-35 seconds
-macOS, one VA instance: 8-9 seconds
-macOS, four VA instances: 11-12 seconds
Note that the Macbook Pro in this case is down about 20-30% in terms of processing power versus the PC. Note also that on macOS, when you activate SC-VA, a Roland subfolder will be created in your Applications folder, and this contains "Activator.app." I suspect that the way Roland has implemented its copy protection on macOS has resulted in a slightly longer load time per single instance but much better load times in cases where more than one instance is present in a project. Granted, I'm just one user, but what a difference in my case!
3) If you are running Windows 10, it should be possible for you to install the SC-D70's Vista 64-bit drivers and GS Advanced Editor, which can still be obtained from Roland Japan's website. I imagine that Google translate can help if needed there, but feel free to PM me if you need language help; I speak Japanese. (And of course assuming I'm still hanging around here.) As of this post, there seem to be some good resources to check out for more information on this: the channel SpeedyDTM on Youtube and a tutorial by user 真琴♪さん (Makoto♪-san) on Nicovideo that purports to give a walk-through. (Note that I didn't watch it since I didn't really care anymore by the point I found it.) There's also this page (again, in Japanese) that aims to be a resource for modern OS compatibility with older Roland drivers and software.
Basically, try running the installer(s) in compatibility mode for Vista. Even if the install fails, you can still attempt to manually install via the device manager, pointing it to the resources that were extracted by the installer. With Windows 10, you'll likely have to disable driver signature verification. I'm sure this has been discussed in other threads here as well, so search this forum first!
4) Note to Pro Tools users--Roland does not currently provide Sound Canvas VA in a PT-native format, so it's either host or route the VST or AU into your session, or go with the SC-D70 and treat it like a plain old hardware synth, with the aforementioned caveats.
So in summary, if you're on modern Windows and maybe want the charm of working with real hardware or the absolute real deal when it comes to 88 Pro/8820 sounds, the SC-D70 should be a nice interface, as long as you're sure you'll be able to manage now and in the future when it comes to sound editing either via GSAE or whatever other methods you or someone else may create. If you want something highly portable that works flawlessly on both current 64-bit Windows and macOS, does not require physical MIDI routing or an extra USB port--or an extra power brick!--then the VA is outstanding, albeit slightly wonky with a few sounds, like guitar. I've noticed a few other patches have minor EQ differences that are not purely attributable to the higher sample rate of the VST. For example, some orchestral sounds clearly have more recessed mids. For this, there are various comparisons on Youtube, including a VA vs SC-55 comparison done by Woody's Piano Shack and featuring information contributed by the aforementioned SpeedyDTM.
Hope at least some of that will be useful to any future searchers. Okay, I'm going to go back to being a ghost now.
