regarding a): - e.g. swapping colors requires you to replace with an interim value - you might miss the one rgba value, because you only replaced the hex or r

regarding a): - e.g. swapping colors requires you to replace with an interim value - you might miss the one rgba value, because you only replaced the hex or rgb values - try search + replace for instead of $border-radius-top, when border radius bottom can, but does not have to be set in the same line. And more: - browser prefixes - synchronized animation timing - split in to files and folder hierarchy, but compiling to one file (also makes git merges much easier) - and if you have something with mild theme support it's really handy