Personally, I dont care for castelli and I find myself directly in the middle of size. Large is too big but medium is too tight. I know a lot of people like their gear, so its certainly worth checking out for youself.
As for Rapha, I used to be a very loyal Rapha customer. There stuff is still great and I appreciate their quality, but I now wear other stuff that I find to be equal in quality but more comfortable and a better fit for me. The Rapha chamois is pretty good, the fit and compression of their pro team shorts are nice and the overall quality is top notch. Their jerseys are nice, but a bit loose in the mid core for me. putting things in the back pockets make them sag more than I would have preferred. The nice thing about Rapha is they have several different cuts to offer, from relaxed and classic with shorter sleeve length. They also have their race line which has a race cut and longer sleeve length. Their jackets and vest s are hard to beat IMO, in fact they are the bar for me in which I compare other jackets to.
The problem with Rapha is that it seems to always draw a crowd of protesters such as [MENTION=406877]PepeM[/MENTION]. Notice that he just hates on it, but doesn't give any validity to why he dislikes it? A lot of people say that Rapha is for poseurs and is nothing other than a marketing story. I will admit that Rapha certainly takes an unusual direction with some of their marketing, but do you where your gear based on the image the company pushes or do you wear it because it is comfortable for you?
The other thing you will hear is how expensive it is. Compared to what though? Compared to performance bicycle brands or entry level castelli? Go on competitive cyclist and look for yourself. Almost every brand they offer has a kit that is as expensive or more. You cant compare the cost of a ferrari to the cost of a Kia. If you are comfortable in performance brand or lower cost kits then by all means. If you like the comfort of a top tier brand/kit and find VALUE in something that will last you a while and be very comfortable, then give Rapha a look for yourself. try it on and establish your own first hand opinion.