3DMark 2013
“The new 3DMark includes everything you need to benchmark your hardware. With three all new tests you can bench everything from smartphones and tablets, to notebooks and home PCs, to the latest high-end, multi-GPU gaming desktops. And it’s not just for Windows. With 3DMark you can compare your scores with Android and iOS devices too. It’s the most powerful and flexible 3DMark we’ve ever created.” From Futuremark.com
at £125, it takes it into 7850 1gb territory, I concur with your conclusion, its certainly overpriced, and limited by that 128 bit bus width, for the same money you could get the 256 bit 7850 1gb, the memory throughput is so much better, and will allow the VRAM to be overclocked, SCAN has an MSI 7850 1gb for just £123.34, making this 2gb 7790 variant redundant.
http://www.scan.co.uk/products/1gb-msi-radeon-hd-7850-4800mhz-gddr5-28nm-gpu-860mhz-1024-cores-hdmi-2x-mdp-dl-dvi-i