Just to start discussion:
Gutter icons are nice, but too many gutter icons is… too much.
IMHO, when there is so many gutter icons like the print screen of low profile linting mode, it become almost useless.
Same for BracketHighlighter, I first liked the idea but now find it counter productive.
Add to the equation that only one gutter icon could be displayed per line, and it become a mess when used by more than one plugin.
But I like the idea of low profile mode for linter