Any additional length added between the device and the computer adds potential latency. Shorter, high quality USB cables are always preferred. Adding a hub will unfortunately add length.
Adding a hub also implies that you are going to add more devices onto that USB controller, which means devices competing for the limited bandwidth of that controller. Even something as unimposing as a USB mouse on the same hub can add the annoying pops, clicks, and latency that you want to avoid. Remember. The Macbook Pro you are using might have two USB ports, but chances are they are ALREADY on the same hub... just internally. So, just using both of those ports at the same time has the potential of causing issues. I know. You said everything is already going smooth.
How much latency can it add? From what I've experienced (and read in the last few minutes) no one can say for sure. There are too many factors in the mix.
In the end, if it is working, don't mess with it too much more... meaning it might be on a hub and is working, so don't use the other ports on the hub.