Most mining softwares are heavily optomized already, they are also based on gpu. The best mining software as in a set it and forget it will be nicehash miner. They do benchmark initially and tune up each card for the best performance..180% performance is asking for 2x performance for the price of one, which is not very practical.
You misunderstand. Algorithms don't use 100% of the card. Cryptonight is extremely memory dependent and Lyra2Rev2 is almost entirely dependent on the compute units. Mining just 1 of those algorithms at a time is leaving half of your GPU unused. I know for a fact that I can already get 145% efficiency compared to global hashrates. I'm suggesting that someone optimizes software meant to dual mine complementary algorithms.
A few other miners mainly the Nanox has popped up with a miner claiming the same, that it uses 100% GPU power to mine different from other mining software. If that is the case as I have not tried it yet, it is a welcome change as long as it is legit.
Still mining Cryptonight coins make us consume less energy and the card to heat at a low level, greatly extending the life of the card. With dual mine I am sure this will change to consume more power and to heat more shortening the life of the card.