What we basically are all saying is you really need to know what kind of enthusiast and upgrader you are.
like for instance,
I know that I will never go 4 way SLI unless it is something like a 590 or 690....but even then the cost is so extreme I would much rather do 2 way SLI with 580 or 680s and be set. Heck, right now I am running a 560Ti and most games that I play can be close to ful settings and once I get a second I should be fine with anything I throw at it for another year or 2.
My biggest debate was wether or not I wanted a case that could do the dual cpu as the sr2 and now srx look fun as hell to do something with. However, I have now decided that it is more cost effective for myself to stay with a single cpu configuration because of cost and how I like to upgrade on a more regular basis and I feel like dual cpus would be harder to upgrade from at a cost effective rate.
Now, if you have someone that always wants to push EVERYTHING to the limit with 4 way sli, dual cpu, SSD in Raid 0, overclocked ram, etc....I would say get the STH10 or TH10
the TX10-D would be awsome if you wanted a server on one side and a gaming rig on the other.....especially if you water cool the server....even though that is a little overkill but get a MO RA 3 for the videocards, then the GTX Black ice for the cpus on both sides....
However, I think if I never got a dual cpu for a case as glorious as the tx10.....its almost blasphemy