Go with the S3 if you can. Over the years I had Mackie Mcus, Behringer, Artist series, even an SSL Nucleus. In fact, I had the Nucleus and the S3 for 2 weeks for comparison purposes, I went with the S3.
Although the Eucon implementation is something that is not 100% supported by Steinberg, it still is miles ahead of anything mcu or hui, you can control everything from the S3, even cue mixes, the track coloring is also matched on the S3 leds, wich I consider a must have. Paired with a Dock and iPad, you have everything in your hands, you can macro almost everything, key command almost everything, it really is a game changer unlike the hui or mcu protocols. I do Post work, it’s the perfect controller for tracking VOs, ADRs and Artist Performances ( sound check, monitoring, re recording work), and of course, a great tool for the mixing stage.
The downside? Go to the forums before you update anything Eucon/Steinberg related, at this point and from personal testing, it’s all good.