I think they'll be fine. I fish with a 7'-0" 1wt, and I'm 6'-1" tall. I also fish a 6'-6" 2wt with no problem. My primary summer rod is a 7'-9" 3wt. They have nothing to compare to, so they'll adapt easily. As you said, you can always upgrade if they want longer rods, and the price is definitely right.

Joe