I've tested gputest on my laptop on Kubuntu 12.10 and Windows 7.

Everything was tested fullscreen (1920x1080)
On Kubuntu, I used the phoronix test suite and on windows the gputest gui.

Both Kubuntu and Windows used the 13.4 amd drivers.

Gimark:
intel hd 4000 (windows): 382
intel hd 4000 (kubuntu): didn't work
amd hd 7730m (windows): 1700
amd hd 7730m (kubuntu): 1728

Furmark:
intel hd 4000 (windows):240
intel hd 4000 (kubuntu): didn't work
amd hd 7730m (windows):586
amd hd 7730m (kubuntu): 568

Tessmark:
intel hd 4000 (windows): didn't work
intel hd 4000 (kubuntu): didn't work
amd hd 7730m (windows): didn't work
amd hd 7730m (kubuntu): 2150

Piano:
intel hd 4000 (windows): 64
intel hd 4000 (kubuntu): didn't work
amd hd 7730m (windows): 90
amd hd 7730m (kubuntu): 94

Volplosion:
intel hd 4000 (windows): 138
intel hd 4000 (kubuntu): didn't work
amd hd 7730m (windows): 246
amd hd 7730m (kubuntu): 255


It confirms that amd drivers performance is similar between windows and linux.
It shows also that the ratio (directx performance for hd4000)/(directx performance for hd7730m) is the same than (opengl 3 performance for hd4000)/(opengl 3 performance for hd7730m)

That stops there, because aside this benchmark, opengl 1 is buggy for me on windows with the amd card and perfect with the intel card
and on kubuntu, portal has lags with the amd card and the games I play with wine work far better with the intel card.