I toyed with using data actor blueprints at one point. From my testing it depends on the memory load of all of the blueprints you are spawning. I could have hundreds of thousands of (un-rendered) blueprints in a scene, but at some point the engine starts stuttering from what appeared to be a memory related issue. If each blueprint were 10-20MB in size, then I could have significantly less blueprints than if they were each less than 1MB.
I did not experience any performance issues other than the memory thing.
Realistically, most projects will not run into the issue that I saw. Imagine your worst case scenario for actors in a scene along with the amount of data that those blueprints might contain, multiply it by 10, then spawn that many blueprints in your level and see how it goes.