If you are a couple looking to save money, the iO2 duo is the obvious winner as it offers the same core cleaning tech for less. If you need just one brush and want a bit more feedback from your device, the iO3 is a solid choice, though it does not feel quite as sturdy in the hand.
The iO3 offers a more interactive experience with its light-up pressure sensor. It is a decent step up if you struggle with brushing too hard.
What We Liked 👍
Helpful pressure sensor light ring
Effective plaque removal
Includes a travel case
What Could Be Better 👎
Slippery handle lacks grip
Only one handle included
Let us talk shop
When you strip away the marketing speak, both of these brushes use the same underlying micro-vibration technology that makes the iO series popular. They both feature a round head that does a fine job of scrubbing away plaque, and frankly, if you have been using a manual brush, either one of these will feel like an upgrade.
The real difference lies in the feedback. The iO3 has that light ring which is actually quite useful for letting you know if you are bearing down too hard on your gums. The iO2 keeps things quiet and simple with just the vibration changes, which might be enough for some, but I prefer knowing exactly when I am overdoing it.
The handles and the headache
My biggest gripe with both of these is the handle design. They feel a bit plasticky and smooth, which becomes a nuisance the moment your hands get wet at the sink. I have seen better grips on a garden trowel. Neither of these models includes a UK-compliant plug, so be prepared to hunt for a shaver adapter unless you want to be tethered to a specific bathroom outlet.
The iO2 is a fantastic deal if you have a partner who also needs a new brush, as it saves you the trouble of buying two separate units. If you live alone, the iO3 is a perfectly capable machine, but do not expect a dramatic leap in performance over its cheaper sibling.
The final brush-off
If you are buying for a household, grab the iO2 duo. You are getting two solid handles for the price of one premium model, which is just good common sense. For those living solo who want that extra bit of guidance from the pressure sensor, go for the iO3.
Just remember that no matter which one you choose, you are going to need a shaver adapter, and the replacement heads will cost you a pretty penny eventually.