Just to let you know that I'm running a single pump solution in my rig. The DDC Ultra as spec'd by Marci. I've fitted my pump with Petra's aftermarket top....very nice it looks too. One point worth noting tho, the DDC Ultra performs at it's best if you plumb the inlet into the top of the pump. Many of the aftermarket tops allow you a choice of connection, for example the alphacool top allows you to connect both inlet and outlet into the side of the pump's top.
Check out my thread for details on how I have plumbed my loop (search for Stealth-Li)
Keep us all posted re. what kit you end up buying...and if you've any more questions be sure to post em up in the forum.