Bests & Worsts Reviews from Amazon

The 5100 model (this one) has a single difference to the 4100. It has 3 modes (cleaning, whitening and gum). The whole difference between the 3 programs is duration (2, 2.5 and 3 min). Hard to argue that is worth an extra $20, especially since there is no magic to the times (i.e. it's not like cleaning starts on min 2:01). While it's not a bad product, I'd go for the 4100 and buy a few additional brush heads with the savings.