[Tom Goldman]

Synthetic fluid wont lower the temps, it just survives them better.
200 deg is not that hot, discharge temps coming out of the converter can run over 300 deg. depending on the converter design.

If your concerned about the temp,by all means use the synthetic fluid ,it cant hurt anything but your wallet.
But I would consider a bigger trans cooler[ if you have one ] and get it in the air flow.
Spray the cooler and the trans pan with water between rounds if you have time.