That's my formula, too, B & C plates. I have used most of my PTI dies in the Cuttlebug with great success.
I will say that I got some "mums" dies from PTI that are pretty intricate. I could not get them to cut cleanly. I even ordered that little thin metal plate, but still no success, so they sit unused to date.
My Cuttlebug is several years old and has had heavy use, and even with new B & C plates I don't think the pressure is as great as it used to be.
But I intend to keep using it as it works for every other die except the Mums.
Bugga in OK
"Be kind whenever possible. It is always possible." Dalai Lama