Well it depends on what type of turn based game you are making, hybrid would suite some of the games, while just purely hexes or grids will suite some.
For example, we use A* to find the shortest path to a hex (The A* assumes each Hex as a node). However for traversing through the node we use the nav mesh as we have varying heights which is much easier and efficiently calculated by the Nav mesh system. We also have blockers which both the nav mesh and A* is aware of, to make sure the route is calculated properly. This hybrid also makes sure the navigation doesn’t cut the hexes in wierd angle. It should look correct when moving from one hex to another
IK for animation also plays a role here to make sure the feet sliding on the terrain is handled properly.
Overall I would say you won’t lose performance going hybrid as it is a turn based game. I assume each player at least takes a few seconds to complete their move. If you can however stick to one system, even better. But on a bigger game with more abilities and features, you will eventually find a reason to have both.