Well, I'm now the proud owner of said sack in sexy citron yellow.
Three months may seem a long time to wait but with superb customer service from Hugo Youngman at Esc-Outdoor, no problem at all.
During that time, I've been wildcamping round Snowdonia and Dartmoor using the previous model Z Pack, which Hugo gave me to test out the Z design.
In a nutshell, both packs are extremely well finished and thought out. The packs compression/expansion is really impressive and above all, they fit me perfectly. The Z55 is by far the most comfortable pack I've found and I've tried on loads.
If you're in the market for a top notch new pack, don't overlook the Gregorys!
...Thanks again Hugo...