Fireplaces, Heating Stoves, Flues and Chimneys - Grate Heaters - Do They Work?

My family & I live down in Alabama and we're about to enjoy our taste of autumn weather this upcoming week & finally dry out from the rain, heat & humidity. Time to turn towards better efficiency and heating. I can't seem to find whether there is any validity to these fireplace grate heaters and whether these modified grates that air is blown through really do the job and make fireplaces more efficient. I don't want to waste my time investing in either one of these grates or building my own if this is all bogus science and while I know hot air rises and cold air is drawn in from the bottom; a fireplace still draws air in from every crack & cranny and I'd appreciate any feedback on if this really, really works; thank you!

And if it does work, I gave it some thought to building my own setup, but given the heat output I have to ask what kind of metal piping or flex tubing can withstand 1000 to 1800 degrees? Is metal electrical conduit & joints (elbows, 45s & other degrees) heated-rated enough to work or the aluminum ducting in Home Depot that are designed for flues be made with small enough diameters or more specifically, reducers be made to do the trick?

I have a blower under the unit, but its noisy and it never puts out enough air flow and it feels to me a waste of electricity.

I apologize if my question has been asked before; this is my first post ever at this website and I didn't want to waste money on something that for the moment I know little about and with the exception of this site can find real evidence yea or nea and it's the tail end of 2009 and just maybe there have been some advancements in this sort of stuff.

Thanks everybody and I look forward to reading your answers; take care!

Sincerely,

Bill B.
Opelika, AL