I don’t have another brand comparison to offer. In my limited experience reading about HAs I’ve noticed that mild-to-moderate “ski-slope” HL often indicates open domes to help avoid an unnecessary “occlusion” effect. Plug your ears and speak to get a sampling of that. Open domes do let a broad spectrum of live sound in, so any processed sound in the receivers will mix with the live sound. That’s where latency can be perceived (10-30 ms and up is consciously noticeable, according to The Internet). Below 10 ms, it depends, and may be something you can’t put your finger on in practice.
I’m 3 weeks into my first HA fitting (Widex Moment 440 sRIC), and I perceive subtle differences between PureSound and other modes (like Universal) with respect to the sound of my own voice. I don’t know how much of that to attribute to latency. I do like the way the world sounds when wearing them, and sometimes use the Music mode when out hiking.
And no, hands-free calling without an accessory (like the Sound Assist or COM-DEX) isn’t available for Widex users. That said, I use a BT boom-mic headset (Sennheiser MB Pro 1) with my PC, and don’t mind holding my iPhone in a pre-2010 position to use as a mic for phone calls. The outgoing sound quality and voice intelligibility will be better than what a mic behind your pinna is going to pick up (more room reflections for the latter).
So, how does the world sound to you?