As with all e-cigs, the pipe is not perfect. Still have to screw around with carts and filler. Seems to wick about the same as DSE 801s and 901s. Might want to give it a shot with the blue foam cart mod though.
Otherwise, check out the 2 piece cartomizer models. They are much less finicky.
Is there a US retailer selling the 601 right now? I looked at litecig and they are out of stock...