You could ditch the SE player, but I recommend keeping it if you happen to use any Steinberg host(s) (Cubase, Nuendo, Dorico, Etc.). Most Steinberg hosts expect it to be there. It’s quite small in terms of disk space, and it’s good to have it for backward compatibility, and for cross compatibility when exchanging projects with others.
On the content packs…again, I’d keep those SE libraries. They come shipped with various Steinberg hosts, but they also come with the full versions of Sonic 3 and HALion6 (effectively bringing those libraries to ANY host…not just Steinberg ones that came with those base sound libraries).
Case in point: SE Basic has all your General MIDI sounds. The General MIDI mode of Sonic would be rendered nearly useless unless you went in and ‘rated’ a comparable set of patches to replace them. Do you want to lose those?
So…keep the SE Basic set for sure. Some of the others…like SE Artist, SE Pro, SE Hybrid, etc…well…see what they contain and judge for yourself.
Again though…if you’d ever used any of those sounds in the past, or want to share projects with others in the Steinberg eco system, etc…you might end up missing them.
Next in line is a ton of content that is unique to the full non ‘SE’ variants of Sonic and HALion.
The biggest of the bunch I think is the HALion Sonic Factory Content bundle. It’s a big, diverse, and valuable content set…I’d have a hard time recommending removing that.
Next are things like the Eagle and Raven Pianos, Auron, B-Box, Hot Brass, the Model C Organ console, the Studio Strings, World Instruments, etc.
Note, the Eagle and Raven Pianos, and the Model C Organ are the next three biggest libraries in terms of disk space.
When you get to the synths (Trium, Voltage, Skylab, Etc.)…notice how they are considerably smaller in terms of disk space? They’re not requiring as much ‘sample content’ to get the job done. If you don’t use fat synths much, you could ditch those, but don’t expect to see huge returns on disk space.
The non SE content can more easily be added and removed with the Stienberg Library Manager at will without effecting the basic operation of the typical Steinberg Hosts as they shipped.
So…if you’re using any Steinberg hosts…keep the SE content for sure, and evaluate what other things you might ditch.
If you don’t use Steinberg hosts…it’s easy to add and remove whatever you think you might want as needed.
These days, you can manage your HALion content with the Steinberg Library Manager (rather than your OS installer registries). Not sure about Mac, but for Windows, you can tap your windows key, and type Steinberg to find the Library app.