A fighter becoming champ in multiple divisions use to be a special thing that would only happen after both fighters cleans out their divisions by a considerable margin. Even when GSP and Silva were at their height they never ended up fighting. Conor came to the UFC and fought at 145 and then won the title. He then instantly was given a squash match (In retrospect) and won the 155 title. GSP comes back in a similiar situation and beats Bisping for the title , then vacates it almost immediately. Jose Aldo stayed in his proper division and achieved greatness there. He does not need to move to 155 and be outsized to prove his worth, especially at this stage of his career. Max successfully defends his title and the first thing they ask him is if he is going to move up to 155. While he is tall, he is pretty skinny and would be outsized and out muscled at 155. 145 is his proper weight class. Fighters need to pick a division and stick with it. Defend the title 5-6+ times before thinking about moving up.