You get 1-2 centimeters of extra drop with the 58 degree stem, depending on its length. That's a pretty good amount. There's 2 centimeters' extra drop between a B123 and B125, for comparison purposes. There's nothing wrong with a Pearl or other level stem if it fits you best.
In racing in this country, a majority of the bikes are now threadless so choice of quill stem is irrelevant. In Japan, there is often a requirement to use steel stems, so the Jaguars are the only choice. On the other hand, that's keirin, which only lasts a few minutes. When track riders here in the US use quill stems, they most commonly are riding older European frames and will be using level quill stems. When I go to most tracks, it's unusual to see a Jaguar unless some road fixie rider is trying out the track.