I wore both a G5 and a Guardian simultaneously in the ten days or so leading up to switching over to auto on the 670, and I too was impressed—I found them pretty much indistinguishable as to accuracy. This included the fact that they both tended to understate my a.m. DP-induced BGs. Not as much of a problem for the G5, since it wasn’t presuming to run my pump for me, but obviously more of one for the 670 system. I was just always starting the day trying to climb down from 180, which ran up against the slo-o-o-o-o-w correction rate, and left me with a persistently higher A1C than I’d been getting before.
I have read that there’s a known issue with Guardians that they work better for some people than others in terms of longevity, accuracy etc., something to do with individual metabolism, but it’s not something MdT talks about so who knows. At any rate it would help to explain why some people have a great experience and others not so much. Like I say, I had the same DP issue with G5s. Interestingly I recently upgraded to G6 and I can testify that its accuracy is markedly better, including the DP-lag factor, which is significantly minimize if not entirely gone. If I had the ability to integrate the G6 with the 670 I’d definitely give automode another try, but…
Anyway, it is pretty promising in terms of what the options may be by the time I’m eligible for a new pump again. Sucks that the whole system is geared so that you have to wait years to take advantage of these developments, but that’s another topic.