I would suggest you research, and post your future GC questions, in the MF forum. There is lots of information for you there.
In the MF forum, you will find approximately 1/2 the GC owners are running Amsoil in both the engine, and trans.
I do not notice any difference, nor does Amsoil claim any performance difference between Amsoil ATH and Permatran. Both are very good products.
You may notice a difference if you chose to use one of the economy hydraulic oil products, some have reported issues with those.
Many choose to be more confident using their machine in very cold weather with the ATH, but they make no claim that you can reduce your warm up times when using it. The cold pour point of both Amsoil ATH and Permatran are similar.
Amsoil ATH like other synthetic oils, can be used for extended intervals, but without and oil analysis, your left to guess how long to go.
The Amsoil ACD engine oil is the closest to what is specified in the manual. HDD is the popular choice.