I have the Dario meter, but have only been using is as a supplemental meter (I use the Livongo meter most of the time). I see what you mean about it feeling “clunky” to use with the iPhone – takes a bit of use to get the mechanics right, I think. I love the small size of the Dario and the all-in-one (except for the phone) aspect of it.
I took the Dario along with me on a long bike ride – I have a carrier for my iPhone, though I have to take the phone out of the carrier to test. The small meter made taking it along effortless, plus the very small sample size meant that I had a meter that actually worked, despite my sweaty hands! I like this meter, though for now, I think the cost will be a bit much for me to use it as a primary (unless I can get insurance coverage for it).