FW800 connecting to a FW400 device (e.g. a tethered camera) is easily achieved simply with an adapter cable. They're not too expensive, and are sometimes called "6-pin to 9-pin cables".
However, external FW800 hubs so you don't have to daisy-chain all your devices (and can cope with multiple devices that don't have two FW ports) are hard to find. Even most of the FW400 hubs that are around only have 3 ports (i.e. only introduce one extra port!).
Currently I'm using an older 15" MBP with matte screen and 6GB of RAM. With 4GB you can cope with LR and PS with 5DmkII images, but it can run out of RAM every now and then and slow down (especially when you start stitching images!). I'm very happy with the performance of mine at 6GB (but even more would be nice occasionally).
However, I went from a 12" PowerBook to a 13" MacBook before the 15" MBP, and am keen to get back to the smaller size, so I have my eyes on a 13" MBP. I'm prepared to put up with the glossy screen again, as when I'm at my desk I use a 24" monitor with the laptop screen being the secondary display. I have the opportunity to upgrade as I can pass this 15" MBP to my partner.
For me CPU speed and cache size is less important than having lots of RAM and a fast disk. I could go and get the current 13" MBP, but am happy to wait a while longer to see what new option comes out (it'd be a bit silly to buy on the tail of the old hardware if I don't have to). I'll get a FW800 hub (to which I can connect my current FW400 hub as well as my current FW800 and FW400 disks) and the I/O options will be fine for me. Whatever I get will be fitted with 8GB of RAM and a 7200rpm 500GB disk (even if not directly from Apple).