I have the XC with my XT2. I think is a very decent lens for the price, and having that zoom range is handy, and it is very compact. I use it for landscapes.
After a recent trip I did some looking at reviews and saw that the longer end of the zoom range is not that detailed, as I had experienced the same. I will attach a link to two photos of mine straight from camera. Exif data is attached. My copy might be better or worse then average, who knows, but id guess at slightly worse.
If you have the money I think I'd recommend the 50-200mm, especially since you'll be using it at the longer end more often. I will be upgrading at some point.
Dropbox link