If you are on track, a 60 makes you attack the corners more cos it drops in noticeably more quickly than the 70. However, I race with a 70 cos it always feels smoother and more progressive to me. I have a 60 on the 748 and a 70 on the beast just now, and am looking to change my race front onto the 748 cos I just dont want that sudden drop in on hte road.