I couldn't tick one or the other of the boxes – I think the choice has to be made contingent on so many variables. In fact we have painted timber, double-glazed bifolds (with a fabulous retractable pleated fly-screen) at the end of the dining room leading out onto a terrace and a painted timber, double-glazed slider (with a timber-framed sliding fly-screen) on the other side of the kitchen (but on the same axis) opening onto a raised timber deck. Each works really well in terms of function and aesthetics but they would not be interchangeable as the different locations determined which was more suitable – but they have been made by the same highly skilled window craftsman and have given us nothing but pleasure. And on a hot, steamy evening with both open we have the most wonderful cross ventilation.

do you mean internal sliders or hinged doors? what would be the purpose of the wide opening? where will the doors stand when open? do the open doors interfere with movement around both the bedroom and the room from which you enter the bedroom? will the wide opening reduce available space for furniture placement on either side?? only consider a bigger than normal (820mm wide) opening if it improves the space and doesn't compromise movement or furniture for both rooms

if the door is solid wood (you can usually tell because it will be very heavy) and the putty and or timber mouldings supporting the glass is carefully repaired and the hinges and door handles are replaces and sealed all around and the door is painted on all SIX sides with a good quality paint/varnish it should be OK but no door will withstand the full blast of hot sun and rain so hope there is a porch or wide eaves for protection...a light weight hollow door will probably only last long enough to save up for a new door, so hope the retro door works for you...btw make sure the door is resized and installed to suit all the extra coats of paint and have the security door made last as old style door thicknesses can affect the installation requirements and costs of the security door

Oklouise and Sirius, thanks for the ideas. Actually the first one could work us very well, removing part of the wall and having a partition instead of a door. A lot more work but we are pretty handy. Regarding the barn door, most of the people I talked to agreed it might date quickly, unless I use a different mechanism than the ubiquitous black one you see everywhere,maybe.