In Riot you need to do following:

<my-tag>

  <div each={ items }>

  </div>

  // use JS to construct items
  this.items = arr.map(fn) // or how you want it

</my-tag>

And you can also manipulate items on every update. I'm sure that at some point there will be a clear use case where React is a better choice.

So far Riot rendering has worked us perfectly.