Well if you think about it a little with the 50/50 you are spreading out the light a little. By this I mean each bulb has two tubes, one a 10k one an actinic. So if you set the bulbs in correctly you get 10k, actinic, 10k, actinic. If you go with th 10k, 03 actinic option, all of the white will be concentrated towards the back or the front of the tank and the same with the actinic. Now of course they are so close that the light will overlap, by I think the manufacturer includes the 50/50's to spread the light out. JMO
Again the blue is pretty much aesthetics. If you want more blue then go the 10k, 03 actinic route.