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.

Wow I too have the same glass above my doors. Mine are all internal swing doors therefore I don't have your delema. I'm in the middle of renovations and mine are staying. My walls will be dark and modern with all the trim white with the original character and it looks great. With your wall, it's a lot to deal with therefore would suggest replacing the slider with a glass door with timber trim, keep your walls light modern and bright and paint your trim dark (any colour you favour) here is my example to give you an idea of what I'm talking about hopefully you can see the value here is a snippet of my renovation good luck....hope my idea gives you plenty of ideas

A sliding door is just a big window, and if correctly built in (check if the glass is the correct sized for the door if a bit old) with the correct sized lintels this should not be a big problem as the loads would be transferred to the sides, allowing the door to slide easily. Silicon spray (being a Yachtie were we use this stuff everywhere), we now use silicone spray on all our windows in our 1930 home and the windows glide across with one finger before they used to tilt when trying to open them. I would place the door head up to line up with the others and one thing you might consider is placing a window seat, (rebate the bottom channels into the window seat) and have the window seat in and out, place a cushion over the entire seat, should be fantastic and if the deck is built, than no balustrade is required. If it is a stacker slider, i would do the seat for the entire length. So instead of looking a bit funny they will think it was supposed to be like that. We should all think outside the square more often. RAM

Hi Lesley, I would contact a couple of frameless glass door hardware suppliers like Feathers or C. R. Laurence and see if they have something like a clear plastic clip-on seal with an wide brush seal or fin seal. It might also be worth finding out if there is any adjustment on the door tracks which might be able to bring the sliding doors closer to the fixed panel.