No experience with tesla but I have a set of vintage 70's grey bottom non stagger set. The thing was off spec by 5% in resistance all 3 positions. They cloth wires they claim to use are not really cloth wires which you can push back but more like cloth which covers another layer of I don't know what material.
Luckily for me, the guitar itself sounded great acoustically and also with the GFS set installed. Bright with a tight bass, lots of chime and overtones. How they might compare with fralins I don't know but they are good enough for me to not look for something else.
My opinion is that:
Great guitar + average pickup = very good tone
Average guitar + great pickup = average tone.
Psychologically, because of its low price, people will always wonder if its really as good as people claim it to be. But at SGD110 for the GFS set, how wrong could you get?