I think any steady-state cardio, 60 minute step workout will suffice as a substitute. Step Works has a higher intensity level than many of her step workouts, either old or new, but it also has a veeery long cool-down that makes it a shorter cardio workout. I'll bet that Step Blast, with its intensity blasts at the end, instead of the long cool-down, burns as many calories and makes you work as hard. The second combo in SW is quite easy, actually, except for those abductors and knee-ups she adds right at the end. I don't think there's a big enough difference between the step workouts to matter, really. Pick something fun, challenging, steady-state cardio, and about 60 minutes long.
BodyMax step (30mins), and MIC step (also 30 mins) are comparable to Step Works in terms of intensity and choreography. If you have either of those, you could use one of them, with a combo or two from SB to bring the total time to 50-60 mins. Unless you are very advanced, I wouldn't recommend doing both BM and MIC step in the same session.
Sandra