Well, the disadvantage in LB is that you have to configure your Index. The advantage is that you get a spot-on Index, unlike the mess Spotlight produces. Consider my git folders as an example - I am adding them with one level below, so I can get all the project folders with a search in LB. What I don't want to get are all those thousands of same-named files in the project folders, cluttering my search results.
Such things are impossible to granulate in Spotlight and this is why I consider the LB approach superior to Alfred. But you have to think about what makes sense in your search first. Since we already have one Alfred, I would prefer LB to stay that way. Tools which are tailored for power-users are rare these days.