I could say that I'd tried many cheaper "twenty bucks" wireless options with terrible results due to transducer getting every single contact noise on the body of my instruments. The same happened with my hurdy-gurdy mechanisms. A complete waste of money.
As I have another XVive products that worked well, I decided to expend my money in this U8. It is not a bargain at all, but if you think it, this device is still affordable for the results. You can see inmediatelly that you get a well built combo that looks sturdy and crafted with good materials. The contact noises are minimal due to good isolation. The sound you get is clear enough and can be taken by the receiver without interferences in the range of 30 ft.
So, let's say the XVive U8 is a great option for the money and works well on a variety of instruments that the clamp can handle. A good option when you do not want to drill your beloved acoustic instruments.