I agree with you that muffs are generally better for range work. Higher NRR ratings. You’re experience is interesting because the Ottos are supposed to have an NRR of 40dB which is more than most muffs.I’ve been using sordin pro x muffs for my raange ear pro for a number of years and got some Otto noizebarriers this spring as I had a bunch of yard/chainsaw work and I hate wearing the muffs while working in the heat.
The sound is a little more natural than my sordin muffs. I got some aftermarket ear buds from Amazon for a tighter fit. Battery life seems pretty decent. They do not muffle sound as well as muffs and I would not use them as dedicated range ear pro but I do prefer them for use when active. My understanding is inside the ear will never be able to reduce db like a good muff. I plan to use them hunting with aggressively braked magnum rifles as they will work at least as well as quickly jammed in horseshoe around the neck plugs I used previously.
How are the Ottos with background noise like wind or walking through brush? I’d also be interested to know how much battery life you get out of them per charge.