Don't be afraid to try on Shoei. I just bought 3 of them. Last fall I got the urge to try a modular helmet. Went to cycle gear and tried on the Neotc. Fit great and felt comfortable. Found it on line for a bit less. There is some wind noise, especially with the vents open, but hey, we ride motorcycles. And compared to using a half helmet with a neck curtain, very quiet. That half helmet was getting up in years so I thought it time for a new open face helmet also. Cycle gear doesn't have the rj Platinum on the shelf so I took a chance and bought one on line on sale with the thought of returning it if it didn't feel like the Neotec. Lets say I still have it. Haven't used it on the street yet but I have high hopes. My wife liked the RJ so I had to buy her one too.
My point is if you want to try on a shoei 3/4 helmet but there is none on the shelf, try on the Neotec and keep the face shield up. That is how the RJ Platinum will feel.