I had to do the same thing when shopping for a replacement bearing in my BMW motorcycle's transmission. Bearings can get way more complicated than I ever thought.
You should be alright, though. Wheel bearings will give you plenty of warning before any kind of catastrophic failure -- they'll make noise when rolling which gets louder as they get worse, and you can also quickly/easily inspect the bearings for play any time you service the bike. You just grab the wheel at 12-and-6 and 9-and-3, and try to rock the wheel back and forth on its axle in each position. If you hear any clicking or feel any movement that isn't the tire, they're wearing out.
One thing I will say is that if you're properly budget-conscious, you can "restore" the original bearings on a serious budget if they are not crunchy or loose or otherwise damaged. Despite all the literature saying otherwise, if you're careful, you can pop a seal off of a sealed bearing and add some fresh grease to it. I do this with plastic tools so as not to damage the seal, as they usually have steel rings embedded in them that you can accidentally bend. You can push the seal back into its spot gently and the lip will usually pop right back into place.
I also put a thin layer of grease on the outside of the seal as an extra layer of protection to keep dust and moisture out.