I have used the SoCal wide 5 disk brake conversion on 2 cars, my Spyder and more recently my Speedster. The kit works well (requires standard spindles, not dropped spindles). The only real disadvantage I see is the weight of the disk casting, it is heavy being totally of cast iron. I have looked at the aluminum version from Airkewled with the applied steel rotor, weight wise it is much better.
I originally went with the SoCal for 2 reasons, #1 cost, and #2 they offer both front and rear wide 5 disk brake kits with "0" offset, meaning the wheels stay in the same location. I don't have room for the 10mm or 1/2" wider requirements that some of the brake kits have, tires already too close to the fender(s) both front and rear on the Spyder and marginal on the Speedster....
If the Airkeweled is available with zero offset and your wallet can stand the price, that would be my first choice....I think the CB fronts have been reliable, but their rear wide 5 disk conversions have been a problem for Cory, Biker2, and some others so some caution is recommended there...they seperate at the casting line between the aluminum and iron portions of the assembly...check the search feature if you want details on that....