It really depends upon what is behind the cause of the daily swing in the SNR and how that "disrupter's" effect is coupled into the circuit.
Once you have a FTTC product deployed, you then have a metallic pathway from the exchange to the PCP, to the FTTC, through a low-pass filter, to the PCP and finally to your home. That is the telephony "side" of the circuit.
For the Internet access, it is a fibre-optic cable from the head-end to the DSLAM in the FTTC, whence it is converted to a VDSL2 signal which joins the metallic pathway your side of the (above mentioned) low-pass filter, travels to the PCP and finally to your home.
If the disturber, which causes the daily swing in the SNR, is coupled into your metallic pathway on the D-side then we would expect to see an identical effect once the FTTC product is deployed. However if the disturber is coupled into your metallic pathway on the E-side then once the FTTC product has been deployed, we would expect to see the effect on the SNR reduced -- if not absent.
Everything about xDSL is very much "try it and see", hence it is only provided as a "best effort" product. The underlying theory of xDSL circuits is very well known. In practice there are a multitude of reasons why an xDSL circuit does not behave as the theory predicts nor as the end-user wishes.
