A match box was released to help people to synchronize two servos using one single channel; you may control the range of move and the direction it moves. Since the appearance of the computerized radios with 8 plus channels, this match box was almost useless since you can program all the stuff from you transmitter, by example, making work two elevator halves with two servos was a nightmare if you do not have a match box or o computerized radio. If you already own a computerized radio (My JR 8103 works flawlessly) you can set up the mixing for a a dual elevator servos, sometimes one of them will not travel the same as the other but there is more in those radios, like travel adjust and sub trim which will help you to set it up with out the use of a match box.
In the other hand, the match box is of a great help if you are running out of channels in your radio.