Do Fireplace Heater Grate Heat Exchangers work? I see them more often as an alternative to an insert. I've heard from several people it significantly increases BTU to living areas but I'm still not sold on it.
I know the reflector type devices seem NOT to work that well based on feedback but I'm geting poistive feedback on grate types so far.

You are right on the reflectors and firebacks, they are inefficient at casting heat forward. Im afraid i have had very little luck with the heating grates you are referring to as well. The fireback nets absolutely no increase in efficiency, so at least you are moving forward a bit by getting a little increase in efficiency by a heating grate. But lets look at if it is really worth it...
Most wood burning fireplaces (if not a rumford style) are operating at a negative heat gain due to the homes stack effect. The fact of the matter is even if you get an extra 15% heat gain from the heat grate you are looking at barely breaking even. If you are looking to break even then save yourself some fuel and plug the fireplace with a chimney balloon and get a fireplace candelabra with some candles.

I'm afraid if you are looking for wood heat you have to take the plunge into getting an insert or wood stove. An EPA model will get you up to a 70% to 75% efficiency. I wish there were a cheaper way to get there, but when it comes to wood heat, you get what you pay for.

I have seen grate heaters for wood burning fireplaces.[woodlanddirect.com has examples of them].I have fireplace doors that are attached to the brick work,I want to manufacture one.I need tungsten tubing(1.5"-2") diameter and a small inline fan approx 160-200 cfm that will fit the tubing. The whole unit can be mounted just outside the fireplace doors.
Need help finding place to purchase materials.

I don't think commercial ones are made from tungsten tubing. That is incredibly expensive and tough to fasten together.