I'll soon have a chance to try the dexcom, and have been currently using the libre. Hopefully someone may find the comparison of different systems interesting, though i appreciate most don't have the chance to use either, you might still be interested!
I've been using the libre fairly frequently for a year or so now, and due to a few factors had half started considering whether i might try a dexcom. (Dexcom started distributing direct in uk bringing their prices down. There have been a few times where i've been low a while before testing it. Find myself doing more "just in case" checks because of that, etc).
I've currently got a libre sensor on but i will soon be trying out the dexcom G4 for one sensor, which is hopefully 2 to 3 weeks. They are licenced for 7 days but most people can extend them. I will hopefully have an overlap period so i can compare the two systems for a couple of days. I purchased a sensor from dexcom (they sell them in 1s at £51.25 or in boxes of 4 at £205- no difference in cost, and shipping is free) and the transmitter and receiver i'll be borrowing from a diabetic. This will give me chance to find out whether the adhesive is okay, if it stays stuck well, if it drives me mad with the size or with the alarms, if i can restart and get a second week out of it, etc.
Dexcom has alarms and libre doesnt which is the main difference. Libre also stores your readings in the sensor, so you dont need the reader with you to get the whole 24 hrs of data, so long as you scan every 8 hrs you will get all the data. I understand that with Dexcom you only get the data when the receiving device is within range of the transmitter. So eg if you go swimming and leave receiver in the locker you will have a gap in readings for the swimming session, whereas libre will store them all there for you to see when you get out and scan. Dexcom having alarms is a bit of a pro and a con to me, i can see it being both useful and annoying. Libre has a blood testing port built in which i find useful also, i use it for that which saves carrying another thing. It does have a bolus calculator and logging options for insulin and carbs but i find these unusable. The dexcom doesnt do blood sugar tests and i dont yet know about the logging options.
I've attached the dexcom price list. The sensors for libre and dexcom are a similar price, at £101.52 for two libre sensors posted, or £102.50 for two dexcom sensors posted. The difference is libre sensors are sold as lasting two weeks whilst the dexcom are only guaranteed for 1 week, though many do restart and get 2 or 3 weeks out of them this isn't a given.
The big difference is the other bits you need to make it work. For the libre thats just a reader or an android phone. The reader being just shy of £50. But for the dexcom you need a transmitter and receiver. G4 transmitter lasts 6 months, but people often seem to get 12 from it. G5 transmitter lasts 3 months + 3 weeks and cannot be extended. G5 you dont need a receiver if you have an iphone which i do, but the G4 you either need a receiver or build a homemade device to use an android phone as the receiver. Until we added all those costs on, the comparison of libre vs dexcom was looking not too different so its annoying these other costs add up, even if it is lots cheaper than it was before dexcom sold direct.
This is the only other part i can comment on so far. Libre customer service is okay, you can buy online without speaking to anyone which is a plus to me, they do replace faulty sensors, though they dont reply to emails and can be hard to understand on the phone. They are hot on chasing you if you dont get a faulty sensor returned to them though it is easy to return them - pop in envelopes they supply, stick on a label they supply, and stick in a postbox.
Dexcom customer service, they have replied to every email i have sent within less than 24 hours. The technical support is apparently available 24/7. I called following an email and the guy knew what i'd said in the email etc and was really easy to understand, i think he was in america. My sensor arrived with a plastic bit broken off ad it being my first one i wasnt sure if it was supposed to be like that or not so i emailed a photo. A few hours later i got a call saying they will replace it. Unfortunately due to the time difference it was gone midnight by then but i guess it was office hours for them! The replacement was delivered a few days later plus additional sensors, and they dont have the problem the first had so must have just been an odd one.
Thats all i have in comparison so far. I'll update on insertion and accuracy once i've inserted it and done some tests to compare.