I guess Ill throw my .02 in.
Im currently using the 630G, and waiting for the 670G, and came from an Animas Vibe, so Ive used both Dex and Medtronic CGM's. This is anecdotal, but IMHO the Medtronics are more accurate for me, and take half the time to settle in than the Dex did.
Id like to comment on a few things from this thread. First, extending the use of the sensors. To say that Medtronics dont extend beyond their recommended use due to some conspiracy on Medtronic's end to make us "churn through their product" is silly. Dexcom certainly doesnt advocate using a sensor beyond 7 days, and yet many people extend them successfully. NEITHER product is intended to be extended. So, theres no nefarious intent here.
Second, the 3rd gen Guardian sensors. The FDA approved them to deliver and reduce insulin based on their numbers. Think about that for a minute. Thats HUGE. Unless you think Medtronic somehow influenced the FDA to go ahead and approve it even though they suck as bad as some of their last products, I dont have hesitation using them. Is it possible they;ll suck on a large scale? Sure it is. And then they'll be recalled. But the fact they have gone through many trials and having read the reports from users who have used them, it gives me some confidence.
Look. Ive lived with D long enough to remember having to boil my stainless/glass syringes and hand sharpen the needles. Hell...home glucose testing wasnt even a thing until my 17th or 18th year of living with D. What Im trying to say is, IMHO the 670G is probably the biggest advancement in the treatment of D since the original pump, and I, for one, am excited to use it. There are positives and negatives to every pump, every CGM, and every treatment method, and whatever you choose for you is best for you. But it drives me batty when people complain about something that they themselves havent even used (Regina excluded, as it didnt work well for her).
Or it could be Im just a grumpy old man.