A 5870 runs at 420 cpm so a 7950 should run at around 700-800 cpm i guess, which turns a 4 gpu 7950 rig into a 2800-3200 cpm beast beating every "high end" cpu out there easily.
You need 9 32 core c3 amazon instances to get that number, running at roughly 4.5$ per hour, a quad 7950 rig draws around 1.2 KW -> even in sucky Germany lousy 30 Cent per hour. Around the world even below 10.
Come again why this is good? This makes PTS more profitable than LTC and you don't want big farms to switch...this might push out cpus pretty quickly, making it a bit more specialised.