Definitely true–but that statement’s true for Windows-to-Windows designing, as well, if the designer doesn’t chose a standard default font.

So while the point is valid, I don’t see this as a major issue because there are known “safe fonts” that work across all browsers. So long as those are used, testing should still be fairly reliable.

And yeah, while it’s not a perfect guarantee, you’ve at least got a much higher chance of cross-platform design success than not testing for Safari at all.

Heng’s article is interesting — I didn’t realize the rendering engine would be basically the same between Windows and Mac Safari (including the fact that Windows Safari does not use Windows’ built in font-rendering, but ports it’s own Mac renderer).

Heng does provide this caveat: “Of course, if your site looks fine in Safari for Windows, there is no guarantee that it will look fine in the Mac since the implementation of the browsers may differ in some small but crucial details. Indeed, if you code your site using a font that is only available in Windows and not the Mac, the appearance of your site will definitely differ on the Mac since Safari for Mac would have to use a substitute font.”