Yes, Arnold has a similar IPR scaling feature that I found incredibly useful. Two difference controls, "Scale," which literally scales the set pixel dimensions of the render settings, so, if you have your render set at 1920x1080, and set the IPR "Scale" to 50%, it's actually rendering 960x540. Then, "Zoom" which ignores any settings and just allows you to zoom in and out on the image, irrespective of render settings. So, you could then set "Scale" to 50% and "Zoom" to "200%" and have a 1920x1080 preview at half resolution, which would speed up preview rendering considerably and still allow you to get a bit closer to the image. I'd often set my "Scale" to somewhere around 80% and Zoom to 120% and it would give me a nice bump up in speed without really sacrificing much detail.