The drawback to foil is when you're using the resistors with low frequency AC signals. The low TC of a foil resistor is done by bonding the foil to an engineered ceramic that has a complementary expansion coefficient. For DC, the current induced foil heating and the substrate will stabilize thermally, and the resulting TC is low. For very high frequencies, there's also no problem, since the waveform changes so quickly that the foil heating is constant over all parts of the waveform.
However, with low frequencies, the foil and the substrate will not heat uniformly over the entire waveform, and the foil can expand and contract differently at different parts of the waveform, causing the resistance to modulate with the signal voltage. What's worse is that the thermal time constants can cause the substrate to expand and contract out of phase with the foil, actually worsening the thermal effects of the signal current foil heating. This creates third harmonic distortion, and at just the wrong frequency, the effect is worse than simply using a 'normal' higher TC resistor that doesn't try to cancel its TC with an engineered ceramic substrate.
So, for audio or other LF AC uses where distortion is important, foil resistors can perform worse than traditional NiCr films like the Susumus, and can generate more distortion than the amplifiers around them. As far as I know, the Susumus have a low TC by tweaking the alloy and the processing, and not by using a trick substrate ceramic, so they'll have better LF distortion performance than a foil.