Yeh except for the price you can get 2 for the cost of a 280X or similar with 2nd. And use less then 80w
And pay for 2x as many motherboards, CPUs, DIMMs, cases, risers etc to get the same total hash power.
If you are only talking about a single 280X not multiple. Then why would you need 2 full systems?
My recommendation wasn't aimed at those of us that use 3 or 4 gpus per system