I carry about 10-15 pounds to work each morning on my water bottles and rear rack. I don't feel the weight at all when I'm riding, and the bike feels quick and nimble enough - however, my point of comparison is to a old heavy department store MTB that I used to ride as a kid, and I think anything feels quick and nimble compared to that!

I've attached a couple pictures - one without and one with the Topeak bag/pannier. I think one could do light touring without any problems. According to the LBS, one of the pros of the bar-end shifters is how robust they are, and they specifically mentioned how that's great when touring and in the middle of nowhere, to have reliable gear shifting system.

PS: There was no option to change the gear shifters on the Cross Check. Another LBS suggested the All-City Space Horse if I really didn't like the bar-end shifters. The Space Horse is at a higher price point, but he said it's very similar to the Cross Check and in general a better bike. I didn't get to ride it thought because they didn't carry one in my size.