I have a Shoei RF-1000, an HJC CL-Max, and recently an N-102 in the same size (SMALL), and they seem to fit my tiny noggin interchangeably with no issues at all. 1000 mile days in any of them. Of them all, the N-102 is my favourite, followed by the Shoei. The CL-Max is a good lid, but I found it a lot noisier than the others on a long ride, and I also think HJC only uses one size of shell for all the helmets, so the small CL-Max is the same external dimensions as a larger size, which makes it physically the largest of the three. The plus is that there's more foam inside to take up the space, so presumably more protection for my brain...
I'm assuming that the Sy-Max is built on the same size criteria as the CL-Max, and also that the N-102/103 are built on the same molds, but no guarantees.
YYMV, and all the usual disclaimers, etc
Griff