I have jpgs for my book but also have uses for them on other projects and wonder if using aliases in my Scrivener Research folder is preferable to using originals.
I mostly use: Insert Image Linked to File (which is not exactly aliasing, although it depends which usage of aliasing you are using).
For me, there are no drawbacks of using this method instead of embedding the images in the project. The image appears in the Project inline, and there are a bunch of functions available by right-clicking an image.
I guess there might be issues with sync’ing to iOS; but I use multiple macs and keep projects in iCloud, so that’s not a problem.
As a bonus, it keeps backups small.
The advantage of having the images inside the project is that the project is completely self-contained. The disadvantage is that both the project itself and all of its backups can become quite large.
Having images outside the project can make it easier to use different versions for different output documents. For example, you could swap print quality graphics for lower resolution ebook versions by simply renaming a folder on your hard drive.
Scrivener doesn’t care.