Gear

I believe the theory is that for (very) high altitude use vacuum packs won't expand whereas others may. Never heard it reported in practice though.

In terms of space, I find that the vacuum packed meals are actually harder to pack because they are rock-hard unusual shapes. Normal packed meals pack easier as they will mould to the space you have.

Anyways, the pro packs are not available in UK: the Mountain House meals sold here are manufactured in the UK (and don't include Jamaican Chicken and Peas!).