S70 Update
Sorry for being away. We have both the GS6000 and the S70 and can make a good comparison. The GS6000 seems out of date next to the SureColor.
On the S70 the pinch rollers are similar to a vinyl cutter - they slide from side to side and you can determine how many to use. If you are printing multiple layers of ink (adding white and/or silver), you only have a roller at each edge of the media so the media can be rewound backwards to print another layer. We recently printed some automotive decals with a graphic of a wrench, which we printed at 25% coverage, and the customer was delighted.
I like the image improvement technology in the SureColor better than the GS6000. It's more of a gradient mask similar to our flatbed and the Seiko Colorpainter H2 series. The silver works well and so does the white. You get a prompt daily to remove the silver and white to shake the cartridges briefly. It also does a recirculation on a built in schedule. The larger print head does make a big difference in print speeds compared to the GS6000, which also has two print heads. Moving from the GS6000 to the S30 doesn't make much sense in my opinion.
Even though I have Onyx Production House and the printer comes with the scaled down Gamma Print, we are using Caldera. It has special features built in to allow printing of White or Silver and Color at the same time in layers instead of pulling the media back into the printer to print an additional layer.
There is a special paper roll that comes with the printer that is used to fine tune the feed and take up reels so that they are aligned. The adjustment was only off about 1/16" in the front and 1/8" in the back. We never had consistent results in this area with our GS6000. The feed roll on the S70 is also motorized and maintains a customized tension that is set for the media type in the control panel or RIP. The "float bar" that maintains tension on the take up side is ultra light so it doesn't affect the feed of the media, but has additional weights that are clipped on for media that needs more downward pressure such as banner material. All of this extra "engineering" means that banding can be eliminated once a media is "configured". The user can configure 30 types of media on the panel. The colors between the S70 and GS6000 are hard to tell apart, even though the green ink on the GS6000 was replaced by grey on the S70. Hope this helps.