Have got the C7, very impressed with it. I got a large based on their size recommendation and it was far too big - flappy around the middle, arms were a good length though. Exchanged for a medium and it fits much much better, but for some reason the arm length didn't seem awfully different.
In terms of keeping dry and not sweating in it, it's fantastic
The Rapha medium seems to have grown in arm length over the past few years, AFAICT. Probably for my body type, which is tall but narrow. The old medium long-sleeves were an inch short at the wrist, which was a real shame as I love some of those old jerseys.
Have got the C7, very impressed with it. I got a large based on their size recommendation and it was far too big - flappy around the middle, arms were a good length though. Exchanged for a medium and it fits much much better, but for some reason the arm length didn't seem awfully different.
In terms of keeping dry and not sweating in it, it's fantastic