SSM wrote that indeed PAL 50hz games played at 60hz produced no borders and the 17.5% speed increase that NTSC games enjoy.
As for PAL 50hz optimised games (examples they listed were Sega Rally and Duke Nukem 3D, PAL games without the borders on top and bottom of screen and i assume speed adjustment) just run them in regular 50 hz mode, as playing in 60hz would add borders at the side or something.