Are you sure that the 150 figure isn't for the LPF for the LFE channel? This needs to be set to at least 120Hz (some amps allow higher) because the LFE channel may contain sounds up to 120Hz. This is different to the crossover settings for the speakers which are the point where the lower notes get diverted to the subwoofer.
In this case larger speakers wouldn't normally be set as high as 150Hz, though it'd quite possible that it may sound better set to say 100/120Hz than 'standard' 80Hz, you need to listen to familiar tracks and film clips to decide what sounds best to you. The only 'rule' being that you shouldn't change speaker crossovers to a lower setting than the amp's set up has configured, but it's OK to raise them higher.
"Don't believe everything you read on the internet". William Shakespeare 1615