I'm fascinated by all the talk about Theory blazers/jackets lately, in particular the Lanai. Please inform me: What is the sizing like? What are the best styles?

Would a Theory Lanai be something I could consider, or is it not that good for my body type? (I'm 5'4" and have a 35" chest measurement, waist 27/28". My regular size is 4 in J Crew and BR).

Thanks!

ETA: To get one, I think I have to find it on eBay, so sizing advice will be very helpful.