The blessing to those who can speak with the Voice of God, which is speaking by the Power of the Holy Ghost, is not only the spiritual exchange of information and testimony.
God spoke and worlds were created. God speaks and mountains are moved, sickness is healed, and lives are changed. When we speak by the Power of the Holy Ghost, we speak the word of God, as if we were God. And all things will obey us as they do God. Moroni tells us,

"Who shall say that it was not a miracle that by his word the heaven and the earth should be; and by the power of his word man was created of the dust of the earth; and by the power of his word have miracles been wrought?" Morm. 9:17

When we speak with the power of the Holy Ghost, which is the voice of God, we speak with this same great power by which God created all things. All of creation recognizes the Voice of God, which is through the spirit of God. When we speak by the power of that spirit, all of creation will respond to us as if we were The Very Creator, God. One of the promised blessings that comes with the Gift of the Holy Ghost is that of miracles.

"Therefore, as I said unto mine apostles I say unto you again, that every soul who believeth on your words, and is baptized by water for the remission of sins, shall receive the Holy Ghost.
And these signs shall follow them that believe--
In my name they shall do many wonderful works;
In my name they shall cast out devils;
In my name they shall heal the sick;
In my name they shall open the eyes of the blind, and unstop the ears of the deaf;
And the tongue of the dumb shall speak;
And if any man shall administer poison unto them it shall not hurt them;
And the poison of a serpent shall not have power to harm them.
But a commandment I give unto them, that they shall not boast themselves of these things, neither speak them before the world; for these things are given unto you for your profit and for salvation." - D&C 84:64-73
- Taken from "The Unspeakable Gift of the Holy Ghost" by Elliaison (Chapter - The Signs that follow them)

"Let my servant William Law also receive the keys by which he may ask and receive blessings; (1) let him be humble before me, and (2) be without guile, and (3) he shall receive of my Spirit, even the Comforter, which shall manifest unto him the truth of all things, and shall give him, in the very hour, what he shall say.
And these signs shall follow him--he shall heal the sick, he shall cast out devils, and shall be delivered from those who would administer unto him deadly poison;
And he shall be led in paths where the poisonous serpent cannot lay hold upon his heel, and he shall mount up in the imagination of his thoughts as upon eagles' wings.
And what if I will that he should raise the dead, let him not withhold his voice." - D&C 124:97-100

The scriptures are quite clear that the power and gifts of the spirit are given to all those who believe without respect to persons or positions. The only criteria is faith which brings the power of the Spirit.

"And that he manifesteth himself unto all those who believe in him, by the power of the Holy Ghost; yea, unto every nation, kindred, tongue, and people, working mighty miracles, signs, and wonders, among the children of men according to their faith." - 2 Ne. 26:13

Joseph Smith had a terrible time with trying to help people of his day understand that these gifts are based upon the spirit and not the priesthood. He lived under the pressure of an extremely chauvinistic male society, who thought men should be the only ones to exhibit such gifts. At various times, he taught the following regarding the sisters in the Relief Society,

"No matter who believeth, these signs, such as healing the sick, casting our devils, etc., should follow all that believe, whether male or female. He asked the Society if they could not see by this sweeping promise, that wherein they are ordained, if it is the privilege of those set apart to administer in that authority, which is conferred on them; and if the sisters should have faith to heal the sick, let all hold their tongues, and let everything roll on." TPJS, Section Four 1839-42, p.224

"Respecting females administering for the healing of the sick he further remarked, there could be no evil in it, if God gave His sanction by healing; that there could be no more sin in any female laying hands on and praying for the sick, than in wetting the face with water; it is no sin for anybody to administer that has faith, or if the sick have faith to be healed by their administration." TPJS, Section Four 1839-42, p.224

"Because faith is wanting, the fruits are. No man since the world was had faith without having something along with it. The ancients quenched the violence of fire, escaped the edge of the sword, women received their dead, etc. By faith the worlds were made. A man who has none of the gifts has no faith; and he deceives himself, if he supposes he has. Faith has been wanting, not only among the heathen, but in professed Christendom also, so that tongues, healings, prophecy, and prophets and apostles, and all the gifts and blessings have been wanting." TPJS, Section Five 1842-43, p.270