Kristopher I. Guskywrote a review of Castelli Sanremo Speed Suit on August 2, 2012
I agree with the OP completely. I had to return the Gore Xenon 2.0 bibs (Small) because it wasn't comfortable for long distance. I talked with the Real Cyclist Advisor (Aaron?) via IM. He suggested going with any Castelli with the Progetto X2 insert like the Body Paint bibs. I saw the San Remo suit and thought it was too unique to pass up. It's expensive, but some bibs cost almost as much without the added benefit of a jersey. I am 5'5.5" 135-140lbs I wear a Small; I was warned that the legs will probably be a little long, and I do have to agree. My only complaint is I wish there was an option to have the legs 3 inches shorter for us small folk.
It IS tight, but not unbearably. The increased compression means better wicking for cooler rides. Most pleasantly, the wind has nothing to hold onto; there is no flapping of excess material. One pro rider commented wearing the San Remo feels like riding naked. I second that comment whole heartedly. It's such a step ahead of every piece of kit I own I don't want to wear anything else. Finally, the chamois is as good as the Real Cyclist Advisor said; I've never been more comfortable in the saddle. I've never felt faster.