If you are doing the funnels or hurricanes in a CCW direction (looking from the sky down), then the heli is having to put full pitch into the heli to keep the tail pointing down AS WELL as countering the torque of the main head. I have found from looking at videos that if you do a CW funnel, it's not as taxing on the tail. But if your like me, CCW is the easiest way to do them. I have been practicing CW funnels, and I just can't seem to get into them as smoothly as I can CCW ones.
Also, your speed plays a LOT into this. If you are doing them slow, then you shouldn't have an issue. But going fast, you are going ot run out of pitch on yoru tail to hold it.