How to use text to blur image/video below?

I'm looking for reusability as much as possible.

I'm getting close... but, I noticed that the 'Scale Horizontally' and 'Scale Vertically' Character settings don't update from the expression... so you can see in the 3rd image below, the blur inherits the font and size, but not the scaling.  

I'm wondering if more needs to be added to the expression, or if this is a limitation?  Any ideas?  

Here's what I've done.

1. Created the image layer in a pre-comp, and have two layers of the comp.. one at the bottom, and one just above that I've applied my blur.
2. Then, for my text layer, I've applied an outline; the 'fill' is transparent.
3. On the duplicated text, I've applied an expression to copy the text and the style, and apply a fill (see expression in screenhot below)
4. I've parented the duplicated text layer to the original, so if I move (align, etc) the text, they remain aligned.

Initial: (ok.png)

Change font, size, move/re-align.. works as expected.. but when changing scaling.. not so much (close.png)