I dunno... unless the rigs are super efficient like the 750Ti's, the heat and power make it harder to make a profit, but not impossible. There are still spikes in price like whenever a new coin is released. They usually last the better part of an entire day.... longer if the coin turns out to be profitable.
The hash rates of x11 are still significantly smaller than say a R9 290 rig. Sure, you use 400w instead of 2000w, but the reality is that 6 rigs on R9 290's will still have higher profitability than 6 rigs on 750ti's even if you factor in the electricity costs, due to the hash rate difference alone.
750ti's are superior for summer mining to keep things running without massive AC. In the winter, AMD is still king.
And.. the winter is coming.
Nah, 750Ti is still best bang for the buck. Just have to be mining the right algo.