Well, I've been riding since 1970. Raced motocross (in it's infancy), did trials, TT, road racing, hill climbing and enduro. For many years I had no car only a bike, even in the winter. I've ridden from sea to shining sea literally. I've been hit nine times, yeah nine by women drivers and once by a man (a story on it's own). I've seen bodies splattered on the track as well as the roads and lost a few friends along the way.
Here is what my experiences have taught me. DOT approved does not mean

. It's the easiest thing to get. If it does not say SNELL approved I won't buy it. It's the highest in approval and testing.
I started with an open face Bell and after seeing a friends face (or what was left of it), I went to a full coverage Bell star and within months it proved its worth when I T boned a woman running a stop sign. I went face first into the pavement at 50mph. Helmet destroyed, face intact less a scrape on my nose. The front almost ground away from the road and a big crack in the helmet from impact, I had a concussion and could not talk for a day or so but I was alive. My Bell had saved my life.
Skip ahead a few years and a new shoei full coverage and another woman driver hitting me from the rear (stop light) tossing me over the car in front of me and into traffic where my head was run over by a Ford F-150. A DeKalb paramedic on the other side of the intersection came running up and I can clearly remember him saying "I thought you were dead for sure" as I was bleeding from my nose and had put some teeth through my lip so there was blood all over my face. Into the hospital with my helmet still on only to be cut off once I was in the ER.
Quality construction had saved me again and again a SNELL approved helmet that refused to be crushed.
You can by a DOT only approved helmet or the modular crap that will open up on impact exposing the face, yeah sure go right ahead (that's why it's not Snell approved). It's your life. Me, I pay the price for a $500 SNELL approved every damn time. I'm living proof high quality construction and high standards in testing saves lives.
Feels good to be alive, with all my teeth. I've done a lot of research on this, seen a lot of crashes, frankly my life is worth the best. I will not compromise on helmets or lots of leather and protective gear even in the summer.
It's your life, make your choices.