I made a table to see how it compares to other methods of acquiring SP, along with a few training scenarios:
This is much more efficient for older characters than for new characters “catching up.”
Training is still much more effective overall than any injection method. I have a feeling that they’re going to nerf training soon, considering just how much more efficient it is. And they’re starting to talk about it too with regard to SP grinding…
Better start stockpiling your SP.