My wife recent did a couple portrait shots of our daughter on 7D2. She used the Canon 85mm, and the Sigma 35mm, and she preferred to shots she got from the 35mm. So yes, the 35mm can be a good fit for the 7D2... As for whether you'll find the 35mm too similar to your 50mm, only you can answer.

As you have no aversion to Sigma, owning the 50mm Art, what's pushing you towards Canon for the 35mm? Focus? Weather Sealing? The red stripe?