Hi Edward,

I have some experience with the U-probe. It's really durable and perfect for repeatedly penetration. I'd say I love this probe if it's not that expensive. One thing I should point out is, due to the low impedance, the signal recorded from U-probe is not as good as regular single electrode (still all right for isolation). 

I have no idea about the V-probe. Presumably they should be similar except the shank. Hope someone else could share their experiences.

-Ji Dai