Config file - inconsistent behavior with missing values

I was trying to minimize my config file, as I usually only keep key-value pairs that are necessary (e. g. in config files of other coin daemons). I am used to believe that missing keys in config files fallback to default values. I would also expect that the default config file contains the default values. I have following issues with grin behavior:

• Some options can't be removed from config file at all or the app crashes at start. I would be willing to accept this behavior with options that are security related, but log_to_file? C'mon!
• I can't be sure about the default values. I couldn't find any reference which states, that values in config file are the default ones. Well, obviously, because it is not true. You enable/disable API authentication by commenting api_secret_path! It would be nice to have documented default values in the config file (or at least somewhere).

Of course this is not a big issue, but I believe I am not the only one who likes to glance at the config file and see where I have chosen to use non-default values and also have a compact config. Also, the described behavior is unpredictable, which is probably never a good thing. (Do I use the defaults by commenting this out? What is the default, is it this value?)

For context, here is link to my whine on grin forum.