I think the big issue is that people mistake an EDF for a jet engine. A traditional prop will produce far more power then an EDF. All an EDF really is is a small propeller spinning at very high speeds.
Here is a comparison. Breath out through your mouth and feel how much air flow there is, now do the same but this time do it through a drinking straw. Same amount of air, but now its coming out through a much smaller opening much faster. There may be more force behind it, but its like trying to push a car with a pencil. A prop will move a larger amount of air for nearly the same amperage load of an EDF. EDF's just allow for a smaller power plant and can make a scale jet look right instead of having a prop slot or big pusher prop.
The way a jet works is burning fuel in that rush in of air. That air expands and even though the same amount of air comes out the back end (burned up into CO2 and other elements) it being so much hotter it has a larger volume and gives a bigger push.
Not saying the EDF booster is a bad idea, just impracticle. A lot of guys find that they have to do a lot of tweeking with the inlet ducts and outlet ducts to maximize the EDF's performance. I've seen build logs of guys who would have to totally redesign the inlet of their ducts to get the performance they needed. You often hear Josh B talk about cheater holes in air frames of EFDs to get the needed airflow for that EDF, this is what he is talking about.