| I have had great success using TI nickel roundwounds on my Godin A4 fretted. I have been flipping back and forth bewteen TI Acousticore's and TI rounds. I found the nickel rounds to work very well, and provide a much more focused tone, with more midrange articulation, than the Acousticores, yet the Acousticores yield their own unique sonic footprint, with more high and low end focus and warmer harmonics.
Both sets, I should note are very light gauge, and tension. And, the outer winding on the TI rounds in very small diameter, which helps keep out the finger noise most nickel strings would produce on piezo equipped basses.
I have tried other nickel, steel, bronze and copper strings on ABGs and found them mostly unacceptable. This is mostly due to the exceptional lare frequency response and dynamic range of piezo pus, which pick up and amplify every string squeak and fret rattle.
Most ferrous strings when used on piezo equipped basses will produced a noisy, clacky, somewhat brittle tone....with incresed string/finger noise, and a honkiness in the mids. Certain strings like Labella tapewounds are designed to eliminate these occurances by emphasizing the low end of the signal. TI Acousticores are the only string designed for piezo systems, and as such note only play into the extended freq and dynamic responses, but produce deep and warm "organic" tones.
For me the jury is still out....it is down to these two sets ( I do use acousticores on my fretless Godin, but y'know TI flats REALLY sound good there...).
Max | 
