Tabs vs Spaces (yes, again!)

PIG DISGUSTING

{
    int a    = 3;
    int ab    = 4;
    // ...
}


{
   int a  = 3;
   int ab = 4;
}

BEAUTIFUL AND NICE

{
    int a  = 3;
    int ab = 4;
}

Style 1 (all tabs) will look fucked up vertical alignment with different tab widths. Style 2 (all spaces) will look weird to those used to different tab widths. Style 3 (tabs to indent, spaces to align), on the other hand, is made of epic win because it allows one to change the tab width without losing the nice vertical alignment, and those who really like all spaces can easily have their editor auto-convert tabs to spaces.

Style 3 > Style 2 > Style 1. If you use Style 1, you're an asshole.

expansion of macros
Only a problem with shitty macros which are not independent tree branches.

and the complexity of languages like Sepples
If it has a grammar, I don't see the problem.

what if you want to deviate from the coding style?
Since you would have full control over the style, you should change the style rules, instead of trying to work around them.

it has yet to be explained how non-standard
If they follow a grammar, I don't see the problem.

What happens if one editor writes out XML (or EBML, or whatever) that another editor doesn't understand? it's going to be a royal pain in the arse to edit without a compatible editor
You would simply need a parse-tree-format to text convertor (with options for setting style rules), and a text to parse-tree-format convertor.

[..whining omitted..]