Use something like the Tekkeon MP3450i (regulated). There are lots of similar products but make sure the battery voltage is set with dip switch, and not with a pushbutton you have to reset every time. Order the battery with a firewire adapter. Tekkeon has a short cable with a FW400 female on it.
Get an expresscard adapter (FW800 is faster) for your computer. Sonnet makes a good item. The expresscard adapter has a port that accepts the external battery via one of its standard jacks. Now you have a powered FW800 port for the Blad, that doesn't care about the laptop power issues.
If you are shooting untethered, you can plug the FW400 port from the external battery (use a FW400/800 cable) into the back. That gives you a power source that lasts for hours. I actually do this with my P1 back, using the same battery that I used with the Blad.
Really, it is all easy once you get the bits, though you do have an external battery to carry around. I usually tape it to a leg of the tripod.
Phocus vs C1, now that's much more complicated. My own personal opinion is that I hate Phocus and I only dislike C1. However, Phocus does things that C1 can't. Functions that I really miss with the Phase platform include being able to control the Rollei LCS and to focus step an H series lens from the computer screen. C1 has no such capabilities (Phase, are you listening?). However, C1 does other things better. What really makes a difference is the user interface on the IQ back. I find I am shooting untethered much more and that is a big deal.
