@viking65: The possible issue is not what the final volt-value after charging is. The issue is what happens during the charge, especially in the end phase of charging.
A charger does not charge & measure at the same time. It is constantly switching between charging & measuring what the current cell value is.
The original Joyetech charger (and SKU 1270407) switches these modes about every second, to make sure the cell goes not beyond 4.2V during the charge. Also the mA output is (ideally) more and more reduced the closer the cell gets to 4.2V.

This charger SEEM to have too long charge phases (does not test often enough where the cell value is). It MIGHT also not reduce the mA output in the end phase of the charge.
Again, I'm speculating! No one knows what really happens until someone measures this charger DURING the charge.
For me, it makes just no sense to take any risks at $1 price difference. Batteries are more valuable than this.

@Skeeeets: different issue but interesting that we meet here again. :-)) So it was THIS charger, I see... ;-)
Might be that the quality of the electronic components varies. Your's might stop the charge too early, other's might end too late. The latter is the worse since that degrades the cell's lifetime.

I get the impression it's a good idea to always buy the second-cheapest devices at FT. ;-) Vendors can't use good quality materials in the cheapest devices, they need to make money too.