Users of Stack and Nix: seeking feeback on sensible defaults

Users of both Stack and the Nix package manager, I am seeking feedback on sensible defaults for Stack, as follows:

• On the NixOS operating system, Stack’s Nix integration is currently enabled by default. Is that still sensible? I understand that the Nix project advises Stack users not to use its Nix integration, but take a different route.

• Stack’s Nix integration, when enabled, implies --system-ghc (prefer a ‘system’ GHC executable on the PATH (e.g. one in the Nix environment) to a Stack-supplied GHC executable) and --install-ghc (seek to download and install the specified GHC version, if it is not already available). Is --install-ghc a sensible default with Nix integration? Should it be --no-install-ghc (eg fail, if Nix does not have the specified GHC version)?

More radically, is anyone actually using Stack’s Nix integration? I’ve been asked to consider dropping it. However, I would not contemplate that if people are using it; Stack’s Nix integration is easy to support and does not ‘get in the way’ for non-users of the integration.