I tried helmet speakers a long time ago.
I much prefer an in-ear solution as it both reduces road noise and allows you to listen to music or, for me, audiobooks programmed through my phone. As the powers-that-be decided to eliminate the convenient but unsightly and leaky headphone jack, I now have to use bluetooth IEMs. After trying several pair, I determined that battery life was really an issue with these items and I already had a nice selection of earbuds, but they were mostly of the corded variety. I came across some bluetooth receiver/amplifiers that work really well, providing acceptable battery life and good sound. Although I tried several types, I mostly settled on the FiiO BTR3 (from Amazon). Really pretty nice and you can use whatever earphone you like. What I like about a device like this is it's very small, not even as big as a pack of gum and you can put it in a shirt pocket under your jacket with the headphone cable tucked away and not likely to hang up on something. That way, if you have your phone in your tankbag or racked on the handlebar or dash, you can get off the bike without having to unplug yourself of drag your phone half way across the parking lot by accident.
For some reason, I never have trouble putting my helmets on over IEMs, but I tend to favor designs that hug the ear rather than extending outward. I'm no audiologist but it seems to me that if you have helmet speakers turned up enough to overcome the noise of highway speed motorcycling, you're doing damage to your hearing, but that's just my opinion. When I'm not wearing IEM earbud type headphones, I'm wearing foam earplugs, anyhow.