I rarely have issues with maintenance/debugging in LESS -- we always compile on the server end and reference only the CSS file in the HTML page. This makes it so there's always a one-to-one correspondence with the webpage and a file on disc.
And then when I have to edit the LESS file, I find that LESS, since its pretty much CSS+extra markup, it's quite easy to backtrace anything I'm confused about to the originating statement in CSS. If it's a mixin, it's pretty obvious (since I usually use mixins to prevent having to do all the vendor prefix stuff repeatedly), and then it's just a logical hierarchy since we use the class nesting feature, so finding:
div#awesome aside ul
is as easy as finding:
div#awesome{
aside{
ul{
padding: 0;
}
}
}
(although we try to not go more than 3 layers deep)
I have no real experience with SASS but I didn't like how far removed from CSS it was when I first looked at it a few years back (and haven't been back since...)
