The caps are really difficult to remove, however the top cap has loosened a bit because of the juice lubing the o-ring, which makes it easier to remove now. This way, I can remove the top cap, give the tank a quick rinse under the tap and let dry then fill up with more juice, without having to take apart the bottom cap and CE2.
I would really like to try cartomizers though.. I'm having mixed results with my CE2s in terms of flavor, and they all seem to leak from the connector to varying degrees. This is an issue with the CE2s though, not the tank or design, since the Torpedo tank I have (blasphemy! lol) has the same issue.
Did you watch the video?