I have the Street Creek 24 and it seems perfect for work then an evening trip to the wall but not the first choice for a day's cragging, as Rob says. In terms of a larger version, BD already make the Creek 35 and 50?
When it comes to the Creek 35 and 50 I've got a rather embarrassing confession to make: despite having seen these packs in the flesh several times before I had completely forgotten they existed until I saw your message. I'll tweak the text a bit in light of this, just so it's obvious that alternatives are available - albeit within a different fabric.
I'll also see if we can get one on test, as it'd be good to review one of the larger ones in light of the fact it ticks a lot of boxes for UK trad and sport.
BD also have the Crag 40 that looks somewhat similar but costs quite a lot less. It seems to be made out more normal thick nylon and not the rubbery haul bag stuff that the Creek range are - but BD seems to have a lot of options on things that would make decent UK crag packs!