Hum is horrible. I've got hum even with cleans. Sure did I buy an ISP decimator to help me, but it's not perfect and the situation with P90 is the worst.
My best noisegate is the angle : when I look to the south west, hum is reduced by 90%, unfortunately it's not very convenient here and if i move just a little, hum is back.
All my guitars are shielded and my single coils in intermediate position and humbuckers work well hopefully.
The good point, now I don't fear hum in any venue :)