I'm wondering if there's something that refreshes the browser when you make changes to the CSS files _before_ saving? Like CSSEdit (which I've used religiously for the past 2 years), but applies to all sort of files (HTML/HAML, SASS/SCSS/LESS).
I do agree that rolling CSSEdt into Espresso isn't the same. I don't know why but I liked CSSEdit better when it was a standalone app. Anyway, as an alternative to CSSEdit or the other desktop apps that give you the instant refresh, you could always write a shell script that watches your working directory and executes the LESS (or SASS/SCSS) compiler then refreshes your browser. I actually used that once but lost it while formatting the laptop it was on. The part that watches the folder and executes the compiler is easy but I had someone else help me with the browser refreshing part.