Pat, Welcome to the forum.

For the ease of repair/replacement an external BB would require fewer special tools you'd need to carry. They also fit standard BB shells and you could carry a second one with little weight penalty. WRT your question of whether an external BB is better than an internal one, I don't know. External BBs are fairly new and don't yet have a broad experience base, but the signs are good so far. I think that if you are going to use an external BB you should have the BB shell faced to insure they're parallel.

Brad