I personally enjoy the anodized finish of the Lian Li a bit more than the industrial grade primer powder on CaseLabs. I suppose the big benefit to the D600 is a tidier WC'ing setup. That might not seem like a lot, but it definitely helps. I'm not super huge on the Merlin series unless they have a pedestal. I really like having the radiators and pump in their own compartment for ease of use, and to keep the main component area from getting too messy.
It's totally subjective, but I'm at the point in WC'ing where I just want things to be simple, and work well.
With two 290s and an enthusiast socket processor, you're looking at a pretty substantial amount of cooling required. Probably in the range of 700-850W, depending on how much you are willing and/or able to push the processor. With the D600, you could plop a 140.3 on the front and back of the second chamber, which would be adequate.
On the flip side, the Case Labs is a blast to mod, and has replacement parts for literally anything in case you mess up. I will say the huuuuuuuuuuge benefit to CL is the removeable motherboard tray. It's probably saved me 10 hours at least during different builds. I had to swap out a motherboard last minute before a LAN, on a rig that was already fully complete. Big PITA right?
Just removed the CPU block, the GPU, and pulled out the motherboard tray. Swapped processors and memory, slid the new motherboard back in. Got everything up and running within 30 mins of starting the break down. That would have been a 5 hour process otherwise.
*edit*
Also, though the MSRP is one thing on the S8, you'll probably add $50-100 in add ons, between radiator mounts and different options. Keep that in mind. My SM5 is pretty basic in terms of extras that I chose, and it was still $80 more than the base price.
*edit 2*
Also, here's a PC-V7 build I helped a friend with.
It's pretty glorious just in terms of fit and finish. Not as well thought out, but damn that craftsmanship. Those Slovenes know how to build WC'ing parts.
