I see I have not updated the thread.
I cannot honestly claim I can hear a difference in caps with different tolerances. However, due to the position of this capacitor in the RIAA network it was deemed to have as correct a value as possible, which is why I went with the 0.5% capacitors.
The silver mica I ordered are pretty cool, and replaced generic WIMA 10% capacitors. However, since I made a number of modifications to the parts, even though I am happy with the result, I cannot claim the improvement was solely due to the RIAA caps.
According to measurements, the RIAA curve is more accurate in the current iteration [0.5% silver mica instead of 10% WIMA]. And for the cost, really can't complain.