The only good reason to have pull, pull is if you have a tail heavy condition, otherwise servo direct in the tail is the best way to go. If you must go forward with the servo's then you can build or buy a setup that places 0 tension on the servo in a pull, pull setup. This setup comes from a company called SWB manufacturing and sells for $90.00, or as I stated you can build one for just a few bucks if your willing to do the work yourself.
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Bob