Alexi, again this will not alleviate any issues. You are misinterpreting where the bandwidth congestion is, which is on the physical hardware side. Simply "picking another channel" will not fix this issue, nor will is stop Bluetooth from selecting another channel either. Furthermore, 802.11a is not really prevalent anymore, you would be hard pressed to find an 802.11a wireless access point. Using an 802.11n on the 5.0GHz band has been shown to stop the problem. Here is a schematic of the Marvell 88W8787 chip that is included in the surface:
www.**marvell**.com/wireless/assets/8787.pdf
As you can clearly see, the 2.4GHz antenna is shared by the WLAN and the Bluetooth, whereas the 5.0GHz antenna is separate from the 2.4GHz antenna.
-Matt