Yes, you get a perceived gain in privacy, but is that worth potentially exposing yourself to additional vulnerabilities?

Speaking only for myself, and regardless of whether this is actually true (see sibling comment): yes. Absolutely. A non-privacy focused browser like Firefox has vulnerabilities/data leaks by design that are worse than hypothetical ones that I probably will not be subject to browsing my usual benign set of websites.

(Posted from Waterfox)