The Fastlane Rock jersey and Mille GT are a regularFi. The Equipe RS is a racing/aeroFit which is considerably tighter.I have a couple of Fastlane Rock jerseys, a team Qhubeka Replica and the new Mille GT C2 GRUPPETTO all in size S.
I like them but I would like to try a more racing fit jersey, so I am interested in trying an Equipe RS jersey.
Regarding size, I'm thinking of sticking with S.
I wear S in regular Fit and it's fairly relaxed for me. I can wear a thick base layer and not feel constricted.
When I first ordered the Equipe RS Jersey in S it was extremely tight and it had to be exchanged for an M. I felt like I would tear the fabric if I zipped up. The Medium aeroFit Equipe RS is still much tighter than the S in regular fit. Medium is literally skin tight on me and there's absolutely no way could I wear my thinnest base layer under it.