I'm also based in Boston, senior dev (FAANG generalist, ~10 years of experience). I make about $200k plus ~$100k RSU/year on average. Previous FAANG paid ~$140k + ~100k RSU/year. I believe my peers make more, and the info I have on CTO salaries at various startups would put $175k on the low end of the CTO pay scale.

If I were you, strictly from a financial point of view, I'd probably test the market to see what offers I get.