So here's my review of the Otto's. I'm 7 days into a 17 day training session so I've run them a little bit.
I got tired of waiting for Ety to release theirs and I knew I had this 17 day session in southern NV where the temps have been averaging 110 degrees for the week. I've been using MSA Sordins for years but didn't want to have over the ear for comfort's sake. I brought the Sordins "just in case" but after the first day I packed them up.
In a word -- they are awesome!! I am using the Comply P Series foam tips for greater sound isolation and comfort.
At the beginning, I fully charged the case and tips (photo attached). Most days the sessions run from 8 am to 5 pm but several days included night shoots until 11 pm. I put them in at 7:45 am or so and except for a hour lunch break, they never come out or got turned off. At the end of a 5 pm day they are at 50% battery life; at 11 pm, 40%. After 7 days of recharging, the case itself is at 90% battery. That's great IMHO. I'm going to see how many charges I can get out of the case before recharging the case itself. BTW, it's not documented (that I could find) but there is a thermal protection circuit in the case which prevents charging if the case is too hot. How do I know? After a day at 118 degrees, I put the ear buds in to charge and put the case in the back seat which was partially in the sun. After about 20 minutes of yacking, I checked the case to see the charge level and there was a thermal overload icon on the screen with no charging occurring. I put the case on a A/C vent while driving and after it cooled, it starting charging.
I originally had the neck lanyard attached but after the second day, I took it off. With the Comply foam, they never moved or got loose. I am not doing stand and deliver either, these are tactical sessions -- throwing yourself on the ground and other barriers, moving and running, weird positions, dragging objects and so on. They stayed put with no problem.
I am only using the low setting. It sounds like normal hearing. I tried high for about 5 minutes and while very loud (to hear commands), the sound attenuation is far too slow for comfort. I can see using high if you're hunting and will only have 1 shot or two but not for range or other shooting.
Which brings up the greatest strength and weakness -- you forget you're wearing them. You really do. No head squeeze, no eyeglass piece digging into the temple, it is so comfortable. It's just another day but the guns don't bother you. On low, attenuation is immediate yet graceful for lack of a better word. Without something to compare the noise with, you don't even notice the attenuation, it just happens. You also have a normal sound field. I can hear shooters in front of me and a car engine behind. For example, with the car I could hear and judge the attenuation. Guns went off and the car sound got quieter then after a second or two the car sound came back up as the attenuation decreased. Like I said, "graceful" is the best way to explain it. On the flip side, because you don't notice them and you just wear them all day, you might forget to put them on after lunch! On one occasion I had to be reminded to put on ear pro. I just assumed they were in because you don't really notice that they're there.
On low it seems like the attenuation happens not just for noises over hearing safe levels but for any major change in sound volume from the prevailing average. For example, we were sitting and talking when people started clapping. Definitely not unsafe but I could tell attenuation happened. There were some sudden noises in a building, again not hearing unsafe but I could tell by the change in ambient noise that attenuation had occurred. IMHO, it's nice they protect across all sudden changes not just at hearing unsafe levels. When it kicks in it's not as though you go deaf, it's just a little quieter then back to normal levels. I'll say it one last time -- graceful.
In a couple of days I change to rifle (AR-15 and similar) so I'll see if there's any change in opinion on them. I expect I'll feel more of the concussive blast since the Sordins cover a fair bit of the head and absorb some of that impulse. I'll let you know.