I rode a Ural with a hack attached a few years at a BMW rally. I've had a couple of older BMW's with sidecars, so I have some idea of what one should "feel" like. The Ural was very different, the sidecare had a drive unit. Even with the drive disengaged, the hack felt really heavy and required a bit of counter steer to keep in going in the right direction. I assume it was set up correctly, the guy had ridden it from Seattle to Spokane and reported it worked good. These things are rumored to be pretty reliable, with the newer ones getting quite good reports. Early imports had various electrical problems.