I've waited a couple months of testing before putting up the review and can honestly say it's a tremendous piece of kit. I've compared these to Altec Lansing and the build quality, design and sound output is superiour.
The battery life is fantastic, it looks brilliant and had a lovely solid build. I haven't heard the other X Mini Max so can't say if the price difference is worth it - I went for this as it's the latest on offer and claims to have better output etc.
Cons: Only gripes are that the little cover that is provided is way to tight to use daily - I use an old camera case to fit the cables, plug and speakers in. The speaker also don't have the same protective guard as earlier models so I guess you'd have to be careful while traveling not to pierce the speaker, but I suppose it let's the sound through without obstruction.
Another problem is that you can only charge all the x-mini ranges via usb which is a real pain on holiday - there aren't always laptops to hand. I had to buy a usb plug adapator to solve the problem - but a decent one will set you back another 5 quid.
It also doesn't have the little audio cable to connect to other x-mini's but does have a port where other x-mini's can buddy jack.