Is there any benefit to using different drivers/blades?

Solution 1:

Different Drivers have different Driver Arts (the attacks on your X, Y, B buttons), each with different effects. Tora, for example, has a Break effect on more of his Driver Arts than 4th Driver.

Also, each Driver has one personal Blade that you can't disengage without some fiddling after Chapter 7. This along with Driver Affinities means that each Driver has some qualities that others lack. While no Driver is head-and-shoulders above the others, they can be specialized to serve some roles that other Drivers can't. For example, 4th Driver is arguably the best evasion tank. Their personal Driver Arts and their Chrome Katana Arts both have an Evasion move and their personal Blade is also well-attuned for evasion.

For now, don't worry about using Overdrive Protocol to move Blades from one Driver to another (also, releasing/Overdriving the 5-star Rare Blades doesn't reset their affinity chart so you don't need to re-grind). Remember that you can only have 3 Blades engaged at a time so hoarding all of the Rare Blades onto three Drivers is a bit of a waste. Start resonating some cores with your new party members and send them on mercenary missions to help unlock their affinities. You don't need to rotate party members since all EXP is shared, even with inactive party members.