I am looking into buying myself a magnum 500. I see that there are two versions of the 8 3/4 barrel. I can get the model with the fixed compensator for 999. The model with interchangeable compensator from diff seller for over 1200. If seller of first model wasn't out of stock of second model it was only listed for 50 dollars more. My question is what are the pros and cons of going with the fixed over the interchangeable.