Both I and my wife use Octo/inflators. My wife uses the Sherwood Gemini exclusively and I switch between it and an Aquatec Air 3.
I have tried others but none that breath better than the Gemini some breath as well but I like the layout of it and find it very easy in use. My Aquatec adds in the extra feature of a built in Sub-duck.(Noise maker) It didn’t breath near as well until I rebuilt it myself and carefully adjusted it to attain better performance.
Early production of the Gemini did have some problems that have long since been addressed.
As for the issues that some divers report in using an integrated octo:
1) you must practice controlling buoyancy while breathing on it. There are options depending on the BCD it is used with. I have found that no matter the BCD or wing there is always a lower dump valve to use to purge air if need be. Others use the pull dump on the shoulder but not every BCD has this available. Finally it is possible to use the buttons on the integrated octo while breathing on it you need to half press the deflate button while slowly and gently exhaling save enough air in you lungs to clear when you release the button or use the power purge. This last method requires the greatest amount of skill and practice since timing of the breathing and control of the button can be critical.
2) You may need a longer corrigated BCD hose on you configuration.
3) if you are heading towards certain specialty diving the specialty requires the use of a standard Octo and/or long hose
I personally prefer a 5’ primary hose with the integrated octo it allows each diver more space since the primary is a donor during a Out of Air incident with a integrated. Be sure the BCD hose length is comfortable for you since it is what you’ll be using during an incident. I’d also suggest occasionally switching to your Integrated Octo at depth and breathing from it so you are familiar with it’s feel and not surprised during and incident.
For Standard Recreational Diving niether a integrated octo or standard type is better it is a matter of personal preference. I tend to agree with the streamlined no dangling school of thought. For this reason I dive an Air Integrated wireless computer and the Integrated Octo and don’t have to worry if a console or octo has come loose and is dragging through sensitive underwater environments.