Well, at first the 18-135 was the only lens I had. I bought it with as a "kit" with the XT1. I used it quite a bit, then came the 16-55 but I still carried the 18-135 for the longer side. But now as I just recently added the 50-140, the 18-135 is in my spare camera bag due to its redundancy. It's great lens to have. I'll probably regret selling it but for now I know it won't be used. I would like to think of it as a "travel" lens but I know myself too well. Even if I kept the lens in my bag I would still bring the 16-55 & 50-140 along and end up using the two much more than the other. I know I'll regret selling the 18-135 when I do but for now, I could use that money to help fund the new 100-400.