Any roto brush expedites the brushing and overall job compared to manually brushing, tenfold, and possibly more. The benefits and considerations to get out the door quicker and easier:
-reduces the amount of scraping
-you can brush more than one ski at a time with a wider roto brush
-you can mount (2) different 10cm brushes on a 20cm shaft
-you can vary the pressure and rpms of the brush relative to wax type and desired results
-you can quickly clean the bases
-you can use a stiffer steel or brass brush for structuring
-a quick release handle is real sweet for swapping brushes
A nylon, a hard horsehair, minimally, and ideally a brass brush, along with a roto cork would cover the basics fairly well for roto-brushes. Maybe adding a felt later and others in between the range if you find the need.
Add liquid wax to the mix and, you’re out the door to ski or in bed sooner the night before and have more time for other things, with far less time and effort.