I wouldn't get a bike if the difference is a intergrated head tube. I don't like it. I like cups and other parts that can get some play and start wearing out to be replaceble. sure you save about 100g if you fit a Record Hiddenset instead of the normal cup version but when it comes to 3-4k, it's not worth it. My C4 with 105 and alot of other cheap parts (including 2ton Exus pedals) only weighs 8.2kg. Yeah, yeah, you do get ligher but I'm not willing to part with my money for a few grams. At this stage my bike already costs more then my car.<br /><br />My advice, get the C4, yoy won't regret it.