Yes, I agree, Amabel is a very nice name. But my other half thinks it looks like a misspelling of Annabel, and that it would be confused for that often. Don't know if this is justifiable...
I really don't think that argument holds any water. I mean, you could pick a very common name like Catherine and have it misspelled and mispronounced all the time. A simple "It's Amabel, not Annabel" would probably be all you'd need to correct people.