Here's a quick rundown of my experience with the CE2's;
The clearomizers dont perform quite as well as the metal ones, but performance is similar.
The clearomizers break/crack way to easily due to weak plastic (G4 is much stronger).
They are too time consuming to refill imo, so much so, I've given up on them and moved to the G4.
They perform great in general, good flavor, TH, vapor.
The inner cap breaks to easily (I don't use a syringe to refill them).
Cutting angled grooves from the wick notches of the inner cap can improve wicking performance.
They can leak quite badly, especially when the weather is warm.
They actually tend to leak more if you store them in the rubber sleeves.
The coil area becomes clogged too often, requiring you to blow through the threaded end to remove the excess
juice.
They can last months if you use clear
juice.
The coil carbonizes very quickly with dark
juice.
The vapor is warm/hot which imo improves the flavor in general.
Sometimes hot juice can hit your tongue if there is juice buildup on the coil.
Removing the middle ring seems to make them perform better.