I have the SBG Street Boxing set, the Denmark seminar and Sparring 101. Unfortunately I haven't had a chance to digest the new Sparring 101 yet, but you cannot go wrong with any of these DVDs. In fact they each complement the others quite well.
The Denmark seminar is an extension of the Street Boxing set. He expands on those basic CM concepts with more advanced techniques. Sparring 101 is an even deeper exploration of these concepts in the context of sparring. There hasn't been very much overlap among the three. The basic concepts of the SBG set are covered with different details in the seminar DVD.
Cannot go wrong with any of them. But after seeing all 3 I will be spending the most time with the Denmark seminar and Sparring 101 with an occasional refresher of Street Boxing.