The miner has been running on my test rig now for 2.5 hours.  It has one Gigabyte WF 270 non X and three Sapphire 270x cards.  The Gigabyte is undervolted to 1.075 volts and the 3 Sapphires are undervolted to 1.100 volts.  Engine clocks down just a bit to find stability.

Running BAMT 1.6.0 upgraded to the 14.6 beta drivers, using this procedure:

http://www.reddit.com/r/BAMT/comments/28xu3i/add_amd_146_drivers_and_djm34s_optimized_sgminer/

Config:

{
"pools" : [
   {
      "url" : "x",
      "user" : "x",
      "pass" : "x"
   }
],
"xintensity" : "512",
"kernel" : "x11mod",
"lookup-gap" : "2",
"shaders" : "1280",
"worksize" : "128",
"gpu-threads" : "2",
"gpu-engine" : "1050",
"gpu-fan" : "20-85",
"gpu-memclock" : "1250",
"gpu-powertune" : "20",

"temp-cutoff" : "92",
"temp-overheat" : "89",
"temp-target" : "75",

"api-listen": true,
"api-port": "4028",
"api-allow": "W:127.0.0.1",
"api-mcast-port" : "4028",
"auto-fan" : true,
"expiry" : "1",
"failover-only" : true,
"log" : "5",
"queue" : "0",
"scan-time" : "1",
"temp-hysteresis" : "3",

"failover-switch-delay" : "30",
"no-pool-disable" : true,
"kernel-path" : "/usr/local/bin"
}


Each one hits 2.55 MH/s