I think you overlook one combo here...
Splinter Twin + Goblin Sharpshooter + any sacrifice.
Enchant Sharpshooter with Splinter Twin. Make copy of sharpshooter. Sacrifice copy for mana, +1/+1, Goblin Bombardment or smth other. Untap sharpshooter and repeat. Aditional infinite ETB, Death triggers.
And you can make more then one sharpshooter and deal massive dmg with all copies