Let application code retrieve the achieved compression ratio and the file version. Both are only meant to display as information to the user.
Case in point: Application code should not change its behavior based on the file version number. Because OpenZGY is supposed to hide that information. If special handling is needed then a more specific method will be provided. E.g. you might use stats->fileHasXYZCapability() instead of stats->version() >= 42.
The same rule applies to statistics such the number of empty, compressed, and regular bricks.