You're going to love the Einsteins. I bought one out of sheer curiosity when they first shipped. Now, a few years later my six Profoto 600 compact monos, two Profoto 2400 floorpacks plus heads and a raft of Profoto modifiers have all been sent off to eBay.
Now I'm as happy as Larry with six Einsteins and a bunch of modifiers, triggers etc. Contemporary lighting techniques and the totally viable option of cranking up the iso on the 5D3 means you don't necessarily need two 2400 floorpacks belting out full power to get your shot.
AFAIA there is modifier interchangability between Balcar, Alien Bees, Einstein and/or White Lightning strobes. But with the amazingly low cost of PCB modifiers, this is pretty much a non-issue.
If you wanted another verification, join up and post a question on the PCB Forums. http://www.paulcbuff-techforum.com/