Eric: Just keep in mind that the 13 has a greater wind load area than the 9. While i would think that APS would sell rotors that could be used with the 13 with no problems, if you are in a very windy area or happen to be in a draft pattern, the otherwise "fine" or "marginal" rotor would be pushed beyond its' limits. In such a case, the brake would not hold the rotor in place and you would end up having to re-aim the rotor every now and then. I would specifically mention this aspect of performance with the rotor / antenna combination that you are thinking about prior to purchasing / installing as you've already stated that installation / maintenance may be difficult. Sean
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