I have the otto. I purchased 3 for test users. I have had some on and off issues with it but I've adapted. Mic gain needs adjustment for quality, emergency button doesn't seem to serve any purpose and it feels a little flimsy. I wouldn't trust it 100% for every day public safety use but it works for my limited use.
I also have a Plantronics voyager, it works in general but it connects in phone call mode and kills the battery pretty rapidly. It does not have any ability to PTT the radio from the headset, you use the regular PTT button.
I tried the AINA wireless responder as well, I could get them paired but was unable to get PTT and emergency button working on 2 different units with any of 3 different 5200s, 5300, 5700 and 5800 I have access to. I did like the feel of the AINA but no PTT on a mic of the style was a dealbreaker for me.