Raced on Mach 2CD's back in the 90's. Still have both sets of them, and they're still remarkably true. From what i understand, the 330's are more a time trial rim, being 330 grams (hence the name) they are more slight having a flat GP4 rim type profile, and are lighter than the mach 2's which are approx. 400 grams. The Mach 2's were used by the pro teams of the 1990's and are reputed to be a very strong rim. If the roads round your way are anything like the 'Roubaix cobbled' roads where i live, then i'd go with the Mach 2CD's.