If you attach the chalk bag to your harness, there can be a challenge when attaching it depending on how the straps on the bag and harness are oriented. Pay attention to this before you purchase the chalk bag. This isn’t an issue for the Momentum package, but it is for the Corax Kit and it could be for other harness and bag pairings.
The chalk bag will either line up nicely or sit twisted sideways, again depending on the configuration the particular harness and chalk bag loops. If you opt against the waist belt, before you buy the chalk bag and harness, grab a carabiner and attach the bag to the rear loop behind the harness. This rear loop looks different on many harnesses and brands. If the bag doesn’t sit in a suitable orientation, look for different chalk bag options. Your harness fit is most important, so I don’t recommend you switch harnesses for the chalk bag match. Another solution is put a key chain ring on the harness loop and then attach the chalk bag to the key chain ring.
Petzl harness & chalk bag, using waist belt: 
BD harness & chalk bag, using carabiner: 
Notice how the loop on the Petzl harnesses sit “sideways” as compared to the haul loop you can see on the Black Diamond harness above. If you attach a carabiner to the Petzl loop, it will sit twisted sideways by 90 degrees, possibly throwing off the orientation of the bag. This depends on the orientation of the loop on the bag itself. The Black Diamond and Petzl bags are similar. I’ve seen a Mammut bag that had a strap for a carabiner that work well with the Petzl harnesses but not for the BD harnesses.
This is something to be aware of before you purchase your chalk bag, if you care about the orientation on a carabiner.