The nitecore is 4 bay and actually, sadly, does a better job then my Pila for half the price. Hate to say that but it's true. Every battery comes off at exactly 4.2v...from the pila 4.14 to 4.2. The nitecore is always 4.2. It has several advantages over the xtar, sliders instead of spacers and all the bays are independent, in the xtar bays 1&2, 3&4, 5&6 are linked. The downside is 4 bays versus 6.
Edit: In some sense it has more bays then the xtars I've tried as all bays are independent. If you put a pretty full battery in bay 1 of the xtar and a more dead battery in bay 2 it will change both bays to trickle charge. In some circumstances it can take like 8 hours to charge a battery. So the independent bay thing, to me, is of prime importance.
i'm guessing no issues with 18350 with the slider?