I use the Lee system, but perhaps because they're a british company and therefore well know/well used in the UK or easily available. I'm guessing import would be costly. Couple of points from the thread neuroanatomist provided.
1) You can buy lens covers for about Â£3 which fit over the adapter rings - I prefer this to using the lens cap inside the holder
2) I would always remove the filter holder and the filters when moving around - once scratched, they're next to useless and at Â£50 for a grad filter, or the kit holder, then it's not worth leaving it on. As the video shows, it takes 2 secs to remove and put away.
3) Certainly in the UK, for the Circ Pola, there is a different attachment to the one in the video, which screws on and is therefore more sturdy
4) My circ pola vignettes at 19-20mm. Lee say they have no real solution :-(
But if Cokin is cheaper and the same quality, then your decision may be made - pending stock availability for either product.