I have done that to the finish on a pedal as well. I always drill before painting now.
Noise when raising the sustain knob (lowering the signal level threshold required for the compressor to act on a signal) is expected. Drop the threshold too far and you start amplifying the noise.
Lot's of my builds have switches and other mods that I rarely use. But they still let me find the options I like, as you have done. On my stripboard builds I have taken to socketing critical components instead.
Is it officially finished now? I know it's harder to answer the "how does it sound?" question with a compressor, so I will ask a different question? Do you like it? Or too early to tell?
DC