I've been putting off getting a Cache for a while because my laptop is an in-between size. It is 3cm x 23.5cm x 34cm, which is in between a 6Z (2.8 x 23.2 x 33) and a 4Z (3 x 24.9 x 36.4). CS has recommended the 4Z, but I am a little chary of that-- nearly 1" of excess room is rather a lot, I think? Any recommendations (4Z, 6Z, or something else) would be greatly appreciated! My thanks in advance.