I am a petite female with a short back. Does anyone have a recommendation for a 20-25l daysack with air flow system (for summer use)? Must be compatible with Platypus, and possible hold poles (though not essential)!

Berghaus Free-Flow 25l. Should suit you down to the ground. Pole holes and a internal sleeve for hydration packs. Goes for about £45. I use one for work all year round and rarely suffer from SBS (sweaty back syndrome)

I second ED, on that one.
I love my Berghaus Free Flow II 25l.

Well worth the money.

Yes, nice pack.

Just to post a related question: What about a pack with short back but NOT narrow shoulders? Mrs. O. realised such a backpack is very hard to find ... All manufacturers obviously think that short back=narrow shoulders.

http://www.ospreypacks.com

If you can wait until early next year, Lowe Alpine also has a new range of women's specific sacs coming out then and some of them incorporate a new vented back system. Look interesting.

Osprey packs are good for short backs, they offer different lenghts.

Use a shop that has the yellow Osprey back measuring system cos you usually need to send away for the short back cos most gear shops dont stock them and you dont get to return them once you order it