I'm guessing the answer is no, or else folks would be using it to make displacement map and other reference-layer based effects much easier to work with. Basically I am trying to avoid pre-composing the reference layer.
I feel like the blend effect gets so close, being able to sample a layer and essentially duplicate it's alpha/RGB etc. onto a solid full-frame sized (transform unmodified) 2D layer. The idea would be that I could use that 2D layer as the reference when trying to apply displacement maps to other layers since it is a full frame (transform unmodified) layer the displacement would sample exactly what is seen on that layer.
The blend effect does have a "center" and a "stretch to fit" feature to center the sampled layer, and it can even now include the source layer's effects, but what would be so massively useful is an "include source transforms" feature so that I could move the source layer, have the solid layer with the blend effect basically re-draw that layer onto a 2D solid and use the solid for reference when using other displacement effects.
I guess if AE just added the "include source transforms" into any reference based effect they could just as easily include it in the displacement map effect and not require this weird second reference layer concept I'm trying, but I figured that's harder to ask for.
Does anyone know of a wild workaround to get there?
I've wondered that myself for ages...
But I've kinda settle the matter into "why would they develop that if its exactly the same thing as pre-composing?"
Because its kinda easy if you think about it:
Select the layer with hyerarchy and camera (if present), hit crtl + alt + C
hit crtl + n (adjust if necessary) then enter
hit crtl + v.
now reference that and its done.
Think about it, you may want the layer to have a matte of its on (so, not just transformations), or as for a luma matte, it may need adjustments (so effects too? or not?), how about masks?
The options you'll need addressed quickly add up. I'm guessing they figure it was easier to already have every option available while just pre-composing.