I don't know if this would work or not but here's my current Idea. Note this is for a MAC solution but it might actually already be available for PC.

Using the new expresscard slot on a macbook pro (especially if it's got a new merom processor in it) you could connect a device that allows you to hook up an external PCIe card (MAGMA makes a PCI one amd is supposed to be working ona expresscard/34 to PCIe card http://www.mobilityelectronics.com/expansion/products/expresscard_expansion/1slot/index.html)
then you could hook up a blackmagic card or kona card of your choice and record via firewire 800 to a large raid drive.

I know this isn't as portable as a firestore but I think it may be more portable then a wafian and come in at about 1/2 the price. The only limits I see are the bandwidth of the expresscard slot (supposed to be as fast as the PCIe bus) and how quickly those Lacie type drives can write.

Just tossing stuff out there, what do you think?

Well, it'd be a great idea if it'd work. Unfortunately for us with the MacBook Pro's that don't have firewire 800, we'd be maxed out at firewire 400 since the expresscard slot is being taken up by the decklink or whichever card you choose.

Maybe if you were to record to the internal hard drive then transfer to the raid, it may work, but that's a lot of un-needed down time. I think I'd feel more comfortable lugging my G5 around and setup a system with that if it's in studio or a closed off set. For on the run, your setup may work...