I've just been researching the three alternatives. As I understand it, the Dexcom One has a transmitter that has a battery life of 3 months. The Glucomen Day has a rechargeable one which is an added thing to get wrong, although they supply twi in a starter kit I think. My favourite is the GlucoRX Aidex which has NO battery in the transmitter - just the Bluetooth gubbins, and is powered from the 14 day sensor battery. Neat solution eh? No chucking away good electronics, use a battery in a bit you have to change anyway. and it's a UK company🙂. OK they're made in China but cheap as chips I reckon. GlucoRX's intellectual property will be in this country so hopefully the majority of the profit.
The only downside I can see so far, is the cloud reporting. My endo isn't as impressed with it for her requirements. In fact she said the Libre one "was without comparison". I took that to mean good!