I use the new "enhanced" enlites with the 640g in the UK. (Not sure what's enhanced about them ha)
I've also used Dexcom system with the vibe.
I had a few issues when I started with the enlites, I now position them in my upper arm and I don't have the issues I had when I first started using them on my stomach, I often restart the sensors on the 6th day and can average 19 days out of a sensor if I wish.
With the enlite, it pays to ensure that the ISIG values are in the right place when you calibrate.
These days I am comfortable enough to bolus from my SG value, as the majority of the time they are inline with my BG readings.
There are numerous videos on youtube about getting the best of the sensor, they are more finickinetty than the Decxom for sure, but I have no real issues with them these days.