Hi, for your info, I ride a GoldWing Trike with Lehman conversion with drum brakes. I ask our GoldWing dealer the same question about changing to disc brakes on my trike. He ask me why? He said most people preferred the stopping power of drum brakes because they thought they stopped better than disc brakes. Much more shoe surface against the drum. That`s what I was told. I rode a Trike at the dealer with disc brakes and I really could not tell much difference.
If you ride in the mountains and are heavy on the brakes they can fade/stoping power from heat buildup.....But the worst problem is in the rain, They will lose considerable stopping power when wet.....