In researching physical frames that are currently available I came across the following:

• Movie poster frames that are front loading i.e. you don’t have to take them down from the wall to change the poster that’s being displayed. Around $85 for a 27 x 41 inch frame from http://www.spotlightdisplays.com
• In the UK, front loading frames for business are known as ‘snap’ frames. An A0 (23 x 33 inches) snap frame costs around £30 from http://www.tradeframes.co.uk. A 27 x 41 inch silver snap frame costs £35 (on offer) from http://www.sign-holders.co.uk
• There are also swinging display racks in which you can have instant access to a large number of pictures. However these tend to be quite expensive. For example, a 50 picture system costs $695 from http://www.clevelandskyline.com
• I also came across variety of possible products in Staples including a Nobo flip chart board which you could use to suspend pictures on (somehow) at around £60; a Cork board (600 x 900 mm) at £44; an A1 clear presentation slip case at £5.50, and an A1 presentation case.
• A standard frame of 36 x24 internal dimension, and a with a beech-type moulding measuring 40mm wide and 30mm deep, can be obtained for £33 from http://www.frame-company.co.uk/beech-36×24-frame-with-white-mount-cut-for-image-size-30x20_1.html
• I did NOT come across any frame that also offered poster storage to its rear.

So, my conclusion after initial investigations of frames is that I need to decide between a snap frame which enables the contents to be changed while still fixed to the wall, or an ordinary frame which probably would look nicer but which would need to be taken down to change its contents. I think I’d like to take a look at a snap frame before making the choice.