If you don't want to risk a crash, you should check the bearings from time to time. On longer trips I would recommend carrying a set of spare parts. If you use high quality ones from SKF they will last very much longer than the original ones. The exact part numbers for highest quality (double coated) type are:

At least the german workshop handbook has some typoos in this section! Also please note that typically the rear sprocket bearing doesn't break down, so you don't have to carry one.

You should also ensure to use new sealing rings when changing the bearings:

Since the expansion coefficiant of aluminum is greater than that of steel, a bit of heat might help when removing stubborn bearings (bearing = steel; hub = aluminum). Carefull - don't overdue it with the heat! Gently heat up the complete hub - and don't burn your fingers - use gloves ;-) When you put the bearings (keep them in the original plastic foil to not arouse your leading lady :)) in the freezer a few hours BEFORE mounting them, they will almost slide in with only little force. Physics behind the idea: the low temperature shrinks the bearings and the diameter will be a bit smaller than the hub they need to fit into. Be sure to change the broken bearing BEFORE it falls apart - once the cage is rampaged and the inner ring falls out, you need to weld small "noses" inside the outer ring to be able to get a grip with a punch from the other side of the hub.