Thank you to all who shared. That was very helpful.
Some things that weren't clear in my question factored into the decision:
- I am not looking (at least not now) for rig control.
- I am looking for something with a built-in sound card, so all connections (PTT and the in/out audio) are via the single USB cable.
I had read some reviews that were so-so, but I have more confidence in the opinions of the club, and they are overwhelmingly positive. So a Signalink USB will be my new interface for future portable operations.