I found the sniper was useful for one type of enemy, but otherwise it wasn't so great. I used it mainly to target in on exploding barrels/boxes upon which exploding barrels were balanced. If I could, I would thank Deepground and WRO for being so dumb as to leave such barrels standing around at every opportunity possible and then hiding near them.

And yea, I used the fire materia all the time when magic was needed. The other materia seemed kind of useless. The nice thing about the fire was that if I shot it in a general area that also included exploding barrels, it usually set them off too.