I’m running the Iris 5100 on Mid-2014 MacBook Pro RD 13" with SU Pro 2015 driving a Dell U3415W monitor (3840x1440).
I’ve had zero graphics issues: no lag, freezing, tearing, striping etc. Screen rendering / animation is smooth and quick — at least on mid-sized models (up to ~50MB - I haven’t made any larger models to test their performance).
I’ve also been using it with Twilight for renders, and — as long as you’re parsimonious in your render settings / lighting sources / textures — it produces decent-looking renders in reasonable times. (of course it’s not remotely up to really heavy-duty rendering, but no integrated card is)
But not sure how it will perform with SU 2017: I’m about to download the trial to see if it’s up to the task before springing on the upgrade.
Hope this helps.