I own a 2003 GSF600 Bandit S, I guess pretty similar to your SonĀ“s, so mi advice is High Beam always!!, your son might have every now and then the courtesy to other drivers by tourning the high beam off if you consider you might flash them or if front trafic asks for light switch (by flashing your son). High Beam helps to be noticed by drivers so keep it on although it can be annoying so switch it off if other drivers asks for.