I have full DA 7900 on my bike, so I had the 12-25 put on my race wheels. I don't want to ride my Zipps on all my training rides and need another cassette for training wheels. The 7900 cassette is 450.00+/-(cdn) and the 7800 is far less. I bought the 7800 cassette for over half the price but the shifting wasn't smooth and was pretty noisy. I am going to exchange the cassette unless someone can let me know if they had a better experience doing the same.