A few weeks ago I bought this nice portable router/repeater etc, with hardware version A2.
It was loaded with the 1.06 version of the firmware. On the 
Dutch support page the latest firmware version is 1.06b05. On the 
USA support page there is version 1.07. In the 
release notes I see:
Firmware 1.06
Date:  
Release Notes:
- Fixed DUT issue at repeat/hotspot mode
- Fixed DUT issue of WPS function when MAC address filter is enabled
Firmware 1.07   
Date:  09/05/2013
Release notes
Fixed security vulnerabilities
1.06b05 is not mentioned. It seems to me that security vulnerabilities have to be fixed. However, I don't know if I can apply this version to my device.
Furthermore I don't know how the performance is affected.
Maybee someone here knows?