Horses for courses.
Coincidentally, I've just bought the Dart 2 from Vicol for one of our CC Clients.
This followed Vicol's MD's advise: -
"For domestic, I would normally recommend the dart, its more flexible in terms of manoeuvrability and with the Dart 2, the head is same size as the BS36.
Also if the house has got hard flooring - Kardean, or polished wooden floors, or smooth marble flooring etc, the dart polisher is fantastic at giving a great shine so the one machine with the head does both carpet and hard floor.
also the Dart you can un-hook the head and carry the body like a hip-vac and use the dust brush n hose to do skirting and ledges etc, so it can be more flexible.
BS36 still best for larger areas such as schools and carehomes".
The great thing about the dart, and the reason I may add one to our kit is the fact you can simply work with carpet or hard floor by a simple switch of the head.