Walking and Climbing

They could make it lighter by getting rid of the compression strap that goes over the external side pocket which also makes the pocket inaccessible on the move. Not that hard to fault at all.

Fair point on the compression strap, it might make sense to move it up, if you remove it then there's no compression system at the base of the pack. As far as the weight goes, if you read the review it does point out that it's not ultra-lightweight, but it's reasonably light for a walking day sac with the features it has. It's not really fair to compare to the Crux which is a stripped-down, ultra-minimalist climbing pack.

OK then my Kimmlite 32 - 750g, happy ?

Well if it's not fair to compare it to a climbing sack, how about comparing it to the 54 litre not at all stripped down or even ultra-minimalist Lightwave S54, which has a frame so strong you can sit on the pack without anything in it, side pockets that you can get at on the move, a lid pocket, a compression system that you can operate while the pack is on your back, reinforced base, double ripstop nylon fabric ... oh, and weighs under a kilo. For a pack with twice the volume, hugely stronger, and with far greater load carrying ability. Much harder to fault.

I've just recieved my shiny new Z30 and strange compression straps aside I'm very happy with it, but can anyone tell me without making me feel too thick what the zip just inside the lid is for and the too thin velcroe straps above it?

I use the Berghaus 64zero as my daysack and currently also as my take to work bag.  For me to change daypacks, I'd be looking for something substantially lighter than 640g!