What kind of privacy grantees does Whist make? Having more of the browser in the could could open up new opportunities for snooping either to sell data, or by state actors. Do you have a warrant canary?
Privacy is also one of the reasons we've decided on the hybrid approach. Websites with sensitive information (your bank, etc.) can be used on local, incognito, or Tor tabs, all of which are not offloaded to Whist's servers and run 100% locally.