I just went trhough r&d with audacity model over the last 2 years developing gasser and electric and 700 conversions. when you have all the blades balanced (easier than weighing out a dime bag cause your just using a scale t match weight and a dowel to match cg, the vibes all come from the gears. I've got hours and hours of logs of it. Up until now or possibly even still, the v-bar wasn't recomended or supported on any other airframe than a logo, know why? The belt drives have zero vibes. you put vbar on an align 600 and it'll give you vibrations in the 200-300 range all at the harmonics of tail drives (primarily torque tube) then put the same vbar on a logo and it'll measure 20-30. The difference is night and day. All the products like mikado, vario, 3d rigid are german...... gaui is chineese
Interesting comments. As I say, I've been fighting vibration problems with the Arducopter system, that's the biggest issue at the moment. I don't really understand it because my quad vibrates a lot, I didn't even balance the blades, and it uses flimsy collett prop adaptors, the props aren't even mounted true as the holes are bigger than the shaft. Sort of a worst case scenario. The APM has no problem with that at all.
But the heli is no end of trouble. I've tried a 450, and have a terrible time getting it to work. The 600 is much easier. But still sometimes a problem crops up. It seems to me that it has more problems with the high frequency vibes. Not the main rotors, but anything in the tail drive. Or if a bearing is going out. A lot of post-mortems turn up a notchy bearing.
I think part of the difference is also because vibrations in MR's tend to be accelerations in the X-Y plane. From the prop imbalances, and the props are relatively inline with the CG. On a heli, you get all kinds of vibrations in all directions. And lots of rotational vibrations. With the main rotor above the CG, blade imbalance gives you a rotational vibration about X and Y. Also, the blade forces do the same, such as from tracking errors.
Tabb has about ten state of the art helis but prefers his own MR's. I currently have one very special heli and it is going to be the first of many more. Including one that floats. As I proved with the F1 MR's, if the model is really steady you can get away with no camera mount at all. Nothing I have seen compares with a TDR on asymmetric blades. What could possibly be better - A TDR with a three rotor head.....
With full size heli's the more rotors, the less vibration it has. Hughes 500 is good, AS350 is probably the best. Jet ranger and R22 at the bottom of the list.
Tandem Dual Rotor? Have you seen any hardware for sale? I've been wanting to do this, I know I can reprogram Arducopter to do it. It's just been slow because of the totally custom hardware.
No camera mount? As in, no servos, or just no elaborate vibration damping, etc? You have to be able to tilt it at least? Nice thing with tandem is no more right skid low.
It's all still a bit of a work in progress though, the biggest problem we have is with vibrations. It seems very sensitive, moreso than other controllers, and we have to figure out why. 
