Logically, type sizes from there (and this harkens back to manually setting type) should only be whole or half increments of the base type size (from my earlier example, this is 10pt), meaning appropriate sizes are 10pt, 15pt, 20pt, 30pt, etc, with agreeable modifications when necessary. However, good proportions would dictate that 10, 15, and 20 are too close together and as such designers would not use each, but probably restrict their designs to the highest and lowest point values.
I think it's important to remember that just because there are six included hX elements doesn't mean they should each be a different size. To create hierarchy, try changing capitalization, tracking (spacing between letters), weight, and other available styles in the type family you're working with.
The only notable differences in my approach have been using Compass's Vertical Rhythm (http://compass-style.org/reference/compass/typography/vertic...) and some mixins to opt out entirely or re-initialize scale for individual components. As a side benefit, using a preprocessor allows for a rem-like approach for all browsers.
Nice music reference. Does it make your page feel sad if you use 1.2?
$ms-ratio: $golden;
or $ms-ratio: golden;
?When you bring Modular Scale into your project it will include a number of global variables including $golden with commonly used ratios in design. They're useful to try out when you're experimenting with different $ms-ratios. Check out the list here https://github.com/Team-Sass/modular-scale#ratios
$ms-ratio: $golden
See: https://github.com/Team-Sass/modular-scale#usage