As for Furmark, it stresses the GPU(s) to about 98-99%, which means it works as well as Prime95 does for the CPU. It renders a lot of fur the way Ati tool does to generate heat/load, only it renders an even more obscene image (in terms of required processing power, that is ), and works great to test hardware. No program will ever pass Furmark for GPU load. In fact, that program gets my GPUs up to almost 90C, while Crysis/3dmark/STO will only ever get them up to the low 60s (65 max), and it does it for both of them, too.
Yup, it looks like a good package. ATI Tool can max GPUs too, as it's not capped on framerate, so it's fuzzy cube processes thousands of frames per second on top end GPUs. Still 100% usage of the GPU. But ATI Tool isn't designed to do "torture tests" per say, it's just designed to confirm overclocks, etc. FurMark looks like a better design for GPU torture testing.