Yes, having the open side toward the chaincase allows all of the metal shavings that come from a chain to go into the bearing unobstructed. The oil that gets to the backside has to squeeze by which should filter it some. The sled manufacturers worked this out a long time ago, although there are still differing opinions. Anybody with the seal removed on the chain side should expect to wear bearings out much faster. The magnet on the end of the dipstick grabs any of the metal pieces that come by, but can't get them all. Look very closely the next time you remove the chaincase cover for metal shavings in the bearings.
Incidentally any given bearing size comes in a variety of configurations as far as bearing materials, tolerances, seals, types of seals, and bearing ratings. They are not all created equal. While none of the sled manufacturers make bearings themselves, they do spec out usage of certain versions. Be sure to stick with the same version if at all possible, not just a cheap one of the same size.