Ah, another post about brakes - my favorite topic! When it comes to upgrading brakes for gravel, there are indeed a few key considerations.
First, let's talk about brake pad materials. Organic pads offer superior modulation and quieter operation, but they wear out faster and don't perform as well in wet or muddy conditions. On the other hand, sintered metal pads are more durable and provide better performance in adverse conditions, but they can be noisy and have a less predictable feel.
As for rotor sizes, larger rotors provide more stopping power, but they also add weight and complexity. A 160mm rotor is usually sufficient for gravel riding, but if you're tackling steep descents or carrying heavy loads, you might want to consider a 180mm rotor.
Now, about caliper designs - there's a lot of hype around hydraulic disc brakes, but they're not the only option. Mechanical disc brakes can offer similar stopping power with less complexity and maintenance. However, they don't self-adjust like hydraulic brakes, so you'll need to manually adjust the cable tension as the pads wear.
In conclusion, when it comes to brakes for gravel riding, it's all about finding the right balance between stopping power, weight, complexity, and durability. Don't believe the hype - do your research and choose the setup that works best for you.