I like the dual boa better. The liner boa really helps stopping your foot from moving or your heel from rising. The focus boa has two boas for the boot one for the bottom part of the boot and one for the top part of the boot, so they are not backups of each other they both control different parts of the boots.
There is also some boots that have three boas. one for the top part of the boot one for the bottom and one for the liner. I know k2 makes a boot like that not sure if anyone else does too.
Last edited by djsaad1; 12-21-2009 at 08:10 PM.