I play with a single hand backhand too,...
Advantages of one-handed backhand:
1. It's easier to reach the balls, so it would take less time and effort.
2. It's very easy to get to the low balls, as you hit the ball when it's low.
3. You can control whether you want the ball to land exactly near the net or on the baseline (the distance of the ball).
4. You would have a better and easier slice, as you have taken on playing with one hand.
5. It's easier to do, as it goes with your hand.
6. Your opponent won't know where you are hitting the ball, as you always do the same motion.
7. It's more exciting
Disadvantages of one-handed backhand:
1. It's more difficult to control the direction of the ball (right or left).
2. It's difficult to do at the beginning, as it's either out of the court or ti doesn't get over the net, but once you've done it everything is under control.
3. It needs more power to do.
Advantages of two-handed backhand:
It gives more power and accuracy.
Disadvantages of two-handed backhand:
1. It's more difficult to reach the balls, especially the low ones, coz you have to go very down to get them.
2. Not a better slice, coz you won't be used to using one hand.
Also:
http://www.itftennis.com/shared/medialibrary/pdf/original/IO_27759_original.PDF