Yes it will make your life easier for light - moderate soiling, and give better results by lifting the pile better than you probably achieve with a brush.
However, they're too lightweight for heavy traffic lanes where the pile is particularly crushed, or for heavily soiled carpets (blacktop etc).
I recently bought a small rotowash which weighs about 12kg, with a footprint comparable to a duo - great for domestics but perhaps a bit small for commercial. The extra weight makes so much difference in digging down to spread prespray and lift the pile.