I found Davina's quite gentle and if you are doing a DVD to replace running I think it might disappoint you. My fitness level was ok but not as good as yours by the sounds of it and I found Davina's very easy up until about 30 weeks +, and even then it wasn't really a challenge. I enjoyed is as at least it kept me moving, but for cardio fitness I think a brisk walk would be as effective. From what I remember, the cardio in the DVD mainly consisted of marching on the spot. There were some push ups, lunges and squats, but not many reps and done quite slowly. The reviews on Amazon seem to indicate that people found it more useful in later pregnancy.
I'm doing the Tracy Anderson Pregnancy Project and really recommend it - has 9 DVDs, one routine for each month of your pregnancy. All very low impact but great for keeping arms, legs and bum as toned as possible!