SHA256 ASIC miner, late to play this game.
Scrypt CPU/GPU miner, difficult to make good return.
Scrypt ASIC miner, can still make decent return.
The Scrypt ASIC's I've seen cost more per KHash/s than GPU's. The trade off, I guess, is power/heat.
1. Save on power, yes, for sure.
2. Maybe you have not checked this price: