MAAP Sizing Help!

Hello everyone, about to buy my first set of MAAP gear, switching over from rapha as their new season gear i'm not a fan of.

I'm 5'7, 153lbs, according to their size chart and my waist/hip measurements I'm smack dab in the middle of size S.

However, on their website, they have their model who is almost the exact same size as me but is wearing a size medium here.

It's confusing because when he's wearing other jerseys he's wearing a size small.

Same with bibs. He's wearing a small here but a medium here

I've heard people say to size up, but other people say they're TTS. What size should I buy?