Mate this is the advice I got on the exact same situation.
You are making far too much out of such a small difference. The 157 will probably preform marginally better in powder.. you might notice the difference. But after all its 3cm difference on the exact same board so in the majority of situations theres no way you'll be able to spot a difference.
You like the park, opt for the 154... you'll be able to press it a bit more without losing out on anything outside the park.