Alright now that I have a new computer setup for music and photo production/post-production (not to mention all the lab number crunching), thought I'd blog a little bit about it! I went with the build-to-order option and went with a 6-core/16 gb RAM/1tb SSD/D700 configuration. I went with the 6-core option to get higher clock speed instead of more cores. The downside of adding CPU cores is that there is a tradeoff between clock speed and CPU cores. Some applications will benefit from higher clock speeds and some applications will benefit more from more CPU cores, so you need to decided what you plan to use the computer for primarily when deciding this. The good news though is that the CPU is upgradeable! So you can get everything setup and then upgrade CPU's in the future if you'd like. Doing so will most likely void the warranty but it's not a difficult upgrade (info here). I went with the base RAM for the 6-core option because I plan to upgrade the RAM soon. The RAM is considered a user upgradeable component, and more RAM can easily be ordered and installed after the fact (here is where I plan to order from). The larger SSD was for more storage. I don't know if this can be upgraded in the future, but there are currently no 3rd party options for more internal storage. Even though I may not take full advantage of the dual D700's in the computer for still photos, I like running multiple displays and may start doing some video/3D soon, so wanted to go with the max here. This is also one option you cannot upgrade in the future. Almost have my whole workstation set up so I'll be able to give more thoughts in the future but so far I'm a fan of the computer. It is whisper quiet compared to previous generation Mac Pros and much smaller. The only thing I dislike is the amount of cables going out of it. You end up having lots of things plugged in to it and that means...lots of cables. If you're thinking about ordering one for yourself, you can find lots more in-depth info on the 2013 Mac Pro system over at the Diglloyd Mac Performance Guide.
I ordered mind on Jan 31st and took delivery March 18th for those curious about build/delivery times.