do you really need faster than f/2.8

check out this article I find the last graph very interesting - it seems that starting at around f/2.8 camera manufactures push up the sensor gain to compensate for the fact that the sensors really cant fully use faster apertures. The Sony in the graph seems to really push it up

http://www.dxomark.com/index.php/Publications/DxOMark-Insights/F-stop-blues

--
NEX-7 & Sigma 30mm f/2.8
NEX-5 & 18-55 OSS
And a spare black 18-55