Sad to say, but back to topic...

You can flatten those oversharp notes with a small amount of tape blocking the nearer lip of the holes, and sharpen the flat by boring out the hole a bit...

Or is it sharpen with tape and flatten with the drill?

Hmmm...

Personally, I've come to the point that I'm buying chromatic sets for different gigs. I've never been fond of the tuneable kinds (not that there's anything wrong with them), and having multiple whistles of multiple makes helps cover all weather and area conditions. Expensive, but increasingly worthwhile. Brass whistles sound SOOOo nice in studio, but are almost worthless in the sun.

M