I' m using the 3.7.4 kernel on my guruplug server (same wifi component) and the guruplug hangs sometimes (client use) during the initialisation of the mwifiex module or during the DHCP processing. Marvell developped a "new" firmware bin file for the SD8787 and i find that it hangs less than before with it.
Link for the sd8787_uapsta.bin:
But that didn't solve the hanging problem. I will wait for new mwifiex patchs.