This does not match my experience. I've had Fi for a few months now and I have 0 complaints. I'm in NYC and switched from AT&T, but even when visiting New Hampshire I haven't been affected by dropped calls or bad service.
I have no doubts that if you greenfield it, Google has that flow tested.
Many of us had pre-existing 6's and I think most people with troubles are there. Be thankful you haven't had to interact with support. Individually they're all nice and want to help, but collectively they have no agency and minimal education.
Most people I've talked to with pre-existing devices have had varying degrees of problems.