normally takes a little while for the brake to become the best it can with a fresh grind. the old gunk wears off the pads, and the excess aluminium shards wear off quite quickly, and the brake settles down.
a good trials specific pad like any colour bloxx, heatsinks or coustellier pads will work very well, and the pads will last a couple of months if you ride a lot. the grind may last longer or shorter, really depends on what you ride. if you drag your brake a lot in mud the grind will wear down, but if you're a TGS street rider that rides in the dry, the grind and pads will last longer...