We got sent a demo unit of the TwinDolly Slider and the thing is built like a tank. It is over-engineered to the point where you can mount a 160lb rig on it without any issues.
It's also got a great feature where you can mount to both tripod or light stands, and attach multiple lengths of track together to lengthen/shorten it to the needs of your shot without having to re-mount a different slider, shortening setup times.
It's certainly overkill for a DSLR rig, but its right at home for a larger, heavier rig such as a fully equipped RED, Alexa, etc. It's available with a Mitchell mount, if that's any indication of what it's suited for.
This place in Burbank, CA did a little video on it and gives a good (if brief) look into it:
I have one here in Vancouver, Canada so if you're in the area and want to come check one out in person, just let me know! :) I have the 2.5' & 3.5' lengths and the 4-way Mitchell mount.
