Yes S stands for '****e' and SX stands for '****e xtraordinare' and if you have an eleganza like myself I think that's italian for 'we saw you coming'.
My 55s = no rev counter, no temp guage, no colour coding (STANDARD)
mates 60 ~SX~ = Rev counter, temp guage, digital clock, colour coding (these are X-tra's) guessing thats what it means.