a friend of mine has the alpine attack 50, it fits him well and he's 5ft 8in. its a reasonably good winter/alpine sack, but whether its worth going for an all singing and dancing pack rather than a more stripped down pack in the shape of a crux or POD is a matter for debate.
the cost is a bit OTT, i bought a new POD cragsac off fleabay for £50, you could get a new one for £100 in needlesport. he bought his alpine attack in fort bill for £55 in a sale at west coast leisure..
a better option might be to contact www.aiguillealpine.co.uk, they make the same kind of packs to order for about £120. the sizing could easily be sorted out and you'd get a very high quality pack that does what your boyfriend wants it to and nothing else.
i certainly wouldn't pay £100+ for a lowe alpine sac when the same would buy a POD or Aiguille.