Let's back up a bit. You say the one gimbal is a Freefly 3x w/Radians. So essentially it's the old Radian gimbal. Good unit but if you accidentally wipe the programming or lose receiver bind and don't have a copy of what it was before you're in for a world of work. Parts are becoming more difficult to find, mostly obtained on the used market. The condition of those parts are as described by the person wanting to sell them with nothing to back up the claim. Consider that. If you're going to shoot mostly stills I'd say go for it. If mostly video you might prefer selling the gimbal and setting up something else. At the price you mentioned the Cinestar is a pretty good deal, even if you elect to upgrade a few items. You may have a desire to look at some newer low kV motors and improved ESC's to up the flight time. The platform is definitely in the heavy lifter class with good parts support from places like
http://www.quadrocopter.com
The s800 has known issues with twisting arms. The materiel used and the length does not provide much rigidity. Lack of rigidity causes issues with video and more importantly motors twisting out of the mounts. When that happens you often have a dead copter.
It's difficult to get into serious aerial video on a small budget. It's often tried (being a slow learner I gave that a shot,
twice) but the end result has more money being spent to correct deficiencies that become apparent after the purchase. Those corrections can quickly end up costing more that had one bought higher end initially. If it was me I'd look to the Cinestar with the understanding I would be making some changes, the gimbal first on the list. Something great for video and more modern and brushless will run between $1,800.00 and $3,900.00 depending on the features desired and the camera to be fitted. You might sell the Radian to someone more interested in still photography and offset cost differences a little. For the NEX and GH you mentioned you could do the lower end of the costs mentioned. There's an outfit out of Coto de Caza, CA that's making what appears to be a pretty nice gimbal and intended to be used with the Phobotic controller. Prices seem reasonable and the controller firmware and software would remain functional longer than the frequently copied Alexmos stuff. With only one source for the controller you know you're getting the real deal every time.
If you plan out parting out any of the NEX lenses give me a shout
It's a good foundation and flies well when set up correctly.
