Overlap isn't a bad thing. You don't want to have to constantly switch lenses because you need to zoom in or out just a little bit more... and that may happen a lot with the 24-105, depending on your style. 24 isn't wide on a cropped sensor body. Lens choice is tricky because a lot comes down to personal preference, atleast at the wide to normal range. Another prime to consider is the 40. It's closer to a normal lens than the 50 on your body, is built better, but doesn't let in quite as much light. On our crop bodies we didn't use the 50 wider than 2.5 in general, as it was too soft a lot of the time. The 50 is nice wider open on a fullframe body. If you have no immediate plans to upgrade bodies, the 40 could be the better choice.