I have to admit ... I did wonder the same thing. That function did throw me for a loop when Sass already has the pre-built rgba function inside. If you just name your variables like Luke suggests and use that rgba function ... you don't have to go to the trouble of writing all the other code.

Don't fix what ain't broke if you know what I'm saying :).

Honestly? Some probably won't find any benefit. I find it beneficial because it fits a system I am accustomed to. Something about writing color(orange) is nicer to me than $color-orange.

Full disclosure, I use Gulp so everything is fast off the bat. Experiences will probably vary depending on the tool. That said, I had a predecessor to the font's mixin which I feel extended the compile time. I never tested it, though. Instead, I switched from ruby-sass to gulp-sass(which is libsass, if I recall correctly) and never looked back. That all said, I guess it depends on how often you will call it. I'm not sure how sass works, but if it's anything like JS, a variable should be faster inherently faster, but you may not notice the render speed until you called in 5000 times.

I will look into running some speed tests and get back to you in a few days.

Thanks Jono!