It is for my blog. Originally there wasn’t a way to be able to detect an image placeholder and to replace it with the required blog image: PHP HTML Substitution?
Now you can select Resource or CMS in the image. I have just tried using CMS and entering {IMAGE} in the field (which is what my blog uses to substitute images) and that works (at the moment).
I am mindful that the CMS hasn’t been released yet and so I can’t depend on this to work in this manner once it is released.
So to answer your question, there is a better solution but I need the CMS. 