Nothing is going to get entirely rid of the jello. A rolling shutter is the cause of jello when using the camera incorrectly. If you mishandle the RED cam you will even get jello with that.
Well, to be more precise, the "jello" issues with this camera have to do with the hardware itself. All rolling-shutter, CMOS cameras will have similar artifacts, but the better ones have less. It's the speed of the rolling shutter that determine how bad the artifacts will be. This camera would need a much better chip in order to make the "jello" as minimal of an issue as it on the RED One.
"Jello" on the RED One is not a minimal issue, it's often present. However, it is in tollerance... Just like on the 5D. The 5D has a little more distortion than the RED One but not by much.
You can reduce rolling shutter distortion two ways. First, raise the sensor frequency to speed up read time. Second, shoot at twice the frame rate and drop every other frame. It's doubtful the update will do anything like that.
The 5D is nothing like the D90. You really won't find a lot of people complaining about the rolling shutter. Yeah, it's there but usually not a problem. Just have to be aware of it. The camera has been mounted to cars, dirt bikes, and motorcycles with good results. From my personal experience after months of using it, as long as the camera is used properly it almost never shows up. That's just me though, others may have a different experience.
Watch the videos online, and if it's too much for you I suggest you look for a different camera