When you arrive at a divesite as a sidemount diver you regularly become one of the centers of attention.
Most of the time people are very interessted and at least try to act friendly because of that.
I guess it depends on where you live. I used to get questions and interest about sidemount, but now it seems that folks don't even notice or remark ... I suspect those who might be inclined to want to use it have already gotten their questions answered and made their decisions about how they want to dive. There aren't that many sidemount divers here anyway, and everybody tends to know everybody. So we concern ourselves more with conditions and buddy teams ... which are frequently mixed in terms of diving platforms anyway ...
I'm fortunate in that divers where I live are generally friendly people who don't much care how someone else dives, they're just interested in having fun and hanging out with fun people. As long as you're not a dick it seems like most folks don't much care how you dive.
As soon as someone spots the helmet that can often change competely within minutes.
People simply expect you to leave that in the car and react suprised that you would even consider taking it with you.
Soon the questioning starts and if you ever even remotely shine the light at another diver you are sure to hear about it in debriefing.
Helmets aren't an issue where I typically dive ... nobody wears them. But the water's so cold that everyone's wearing a hood, and those few folks who want a head-mount light just wear one over their hood. I've dived with a few folks going head-mount, and I don't much care for it because no matter how careful they are sooner or later you do get a blast of light in your eyes ... and it's pretty distracting. Besides, I tend to dive with folks who use their lights for signaling, and that's kind've tough to do with the light mounted on your head.
Often you are questioned about overhead training, experience, solo diving...
Solo diving is where I usually get the questions ... often from people who have been conditioned to believe that it's inherently dangerous. Most times they mean well, and so it's not that difficult to respond to their concerns with a few reassurances that I've been diving this way for a long time and I obviously ain't dead yet. After a while, they leave me alone.
If you show to have certs for all of those disciplines conversation predictably circles back to: "Yes, but why use it here? I do not need one...".
If you avoid discussing it, like I do (I never prove any training level to anyone and and to divesite owners I only admit to have cards I really need to make a particular dive), you are soon accused of using it because you are unfit to be diving outside your cert level, which you obviously are, as proven by you owning the helmet.
That is always easy because where I am located even cavedivers rarely use helmets (on prinziple) and dry-cavers rarely talk to normal divers at all (rarely even admid to be divers themselves or pretend to be regular tec or rec divers, often loudly pretend and sometimes look like they are method acting a particular type of "dive site hero" for fun).
Years back it was like that with skiing ... if you weren't racing, why wear a helmet? It suggested a degree of incompetence. Nowadays it's rare to find a skier on the mountain who isn't wearing a helmet.
It has become a habit for me to go on the offensive early, talking about the advantages of the helmet mouted main light in conversation, directing people to paricular videos before meeting them...
My suggestion would be to skip the offensive ... or what sounds more to me like defensive, and only direct people if they show some genuine interest in wanting to dive that way. Otherwise, a simple "it's how I prefer to dive" will suffice, and tends to keep the conversation on more of a friendly tone. And it is, after all, the most legitimate reason for most of the equipment choices we make in scuba diving ...
... Bob (Grateful Diver)
