I picked up the last L in a darker blue polo shirt so can only speak about my item. It is incredibly light but also stretched but I can't imagine the shape changing due to the construction quality. The neck around the buttons is actually pretty tight yet I can comfortably do it up to the top, which is rare for me as I have a massive neck for someone of my chest size. I can't comment on the wannabe body builder part as I lift five days a week so probably am one ;) For someone with pretty big (but not massive arms) and a naturally large frame with some (but not loads of) muscle mass it's brilliant. For other builds I couldn't comment as I've never seen anyone I know of wear one. I'm 6"2.5 & 16st with a 42-43" chest and the L fits me like a glove. Could've been made to order. Couldn't comment on other items. Temped to buy the mid blue crew neck too, but not sure I'll bother with much a small discount and their postage not being that cheap. Think I'll grab a darker shade elsewhere.