RC feedback.

I've got the question about voltage rating's importance for capacitor in RC feedback circuit. In my amplifiers it goes from secondary out transformer circuit back to the input tube grid.
Capacitor that is in parallel with resistor has a voltage rating of 1600DC and 270pf. Why such high voltage rating is being used? What will happen if replaced with smaller voltage ratings?
Back in my tube days, I often used caps with 3x or 4x the supply voltage to provide headroom for transient peaks during power on/off etc. due to the transformer's collapsing field. I'm not sure, but I also believe they have a longer life and tighter tolerances when used in a lower voltage circuit. During repair I used a higher voltage part, but I wouldn't use one lower than the original part spec.