Depending on the operating voltages and applications, even the older film caps can start exhibiting some leakage over time. For me, whether to recap older stock depends on what they might damage if they cut loose. In a line stage app, the risk is low, I tend to worry less, and leave them be if I like the sound. Around outputs, especially with PIOs, you do need to exercise a little more care and supervision. However, Vit-Qs are very robustly made as PIOs go.
I agree with the other poster; if it's a choice between picking a capacitor over an OPT winding made of unobtanium, the cap loses every time.
The Soviet PIOs (K40, etc.) supposedly approach a Vit-Q in both sonics and build quality. That may be a good alternative if you like the Vit-Q sound. At the usual Ebay price, they're a no-brainer. That their very conservative ratings go to a full kV is added peace of mind.
If I had to replace a Vit-Q and didn't want to spend large, I'd drop in some K40s. But my guess is, your Vit-Qs are fine.
I'm not going to touch the differences between a good PIO and an orange drop. Suffice it to say that those who hear differences will rate these at opposite ends of the sonic spectrum.
