Fuzzie said it all really well.
For me, P57 just felt like TOO MUCH (and perhaps it's because I was not fit enough). My thighs burned with BM (in a good way)...but they hurt (
not in a good way) after/during P57. I felt that BM didn't totally overload/overwork my quads so much in one set as P57.
I also like the calmer instruction of BM...but I have to admit that Tanya's chatter didn't bother me (nor did Shellie's). And I really enjoyed the Arm & Ab booster...but just couldn't find room for it in my workout schedule...
I say, stick with the BMs for now, see how you like them for a while....and then move up/on to P57. Besides, P57 (and BM!) should be making some new videos in the near future, so maybe this original set will drop in price