Hi Rob

All the guys here are using 8511's without any issues. The only reason I can think of why they are issue the warning is against hacking out the servo mount to get the the servo in. I did not have to change mine at all, the 8511 dropped straight in. Heading for 70 odd flights on mine and my friend did his 90th flight today using 8511 on rudder. No problems.

Zane