The Medtronic CGM for the 670g are called guardian sensors. I have used the 670g with guardian sensors, and I currently use the tandem t-slim x2 with dexcom g6 sensors. There are comparisons that others in the FUD community have made that you can find by using the search tool here on FUD.
Do you have specific questions about the guardian sensors?
My general overview (if I’m remembering correctly - this may have changed since I used the 670g with guardian sensors, but I don’t believe so) : the guardian sensors last 7 days but take a day or 2 to get accurate, in my experience. The transmitter must be charged in between changing sensors (a few hours+ I think). Insertion hurts more than dexcom IMO. Guardian sensors must be calibrated at least every 12 hours but sometimes more frequently. If not close to the sensor reading, the calibration can cause the sensor to fail early and require replacement I think. The amount and frequency of alarms while using the 670g+guardian sensors were a lot and oftentimes very frustrating.
From my experience, guardian sensors can get inaccurate and have transmission/reception issues in the last day or so. From my comparisons, I think the guardian sensors were ok on accuracy, less accurate than g6 mostly, especially when BGs were moving up or down quickly. But I think I remember the guardian being better or ok in terms of accuracy for lower BGs for me, but I’m not entirely certain on that.
Of course, this experience depends on the individual, their preferences, and their expectations of control. Hopefully the 670g and guardian sensors work well for you!