The original method of creating image feedback is both the clean and advanced one ;). Blend Image with Feedback is mostly a simplified version that does the basic trails and scaling. As color depth directly affects smoothness, the breaking point of feedback, and isn't easily set elsewhere without a blend node - it is absolutely important.
When that is said, the basic "hard" approach for creating more advanced feedback can look something like this:
This enables other displacements of the feedback image, here I'm using "Bulge Image", but any translation will do to offset the image to enable the feedback. This is also the approach you want to use for diffusion/reaction kinds of effects as you can blur/sharpen with each frame iteration.
As far as framerates goes, this should also be a viable approach. You might also have to hold the original image value to sync it up, but that depends on your composition.
No stress! It is a bit of a different thought process. The coordinate system makes a lot more sense both mathematically and when you do 3d manipulations/work in 3d environments. Coming from pixel space and 0 - 1 / Width - Height space to that can be a bit of a shift though! I have ripped out a fair few hairs when transitioning to this kind of workflow myself. As it is standard for most applications in 3d space I guess it's just a matter of getting to grips with it.