To change to cavity doors you will need to remove the wall each side of the doors to accommodate the cavity housing. Normal sliding doors would make a difference but the problem with them is they never stay totally closed and they do become quite noisy and annoying. This problem also applies to double cavity doors. The other option is to use bi-fold doors, they won't intrude into the room as much. Do you really need two doors there at all and is the glass above the doorway necessary? My personal preference would be to fill it all in and just have the one door to the room. You could even re-use one of your doors.

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

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.

If it is bare particleboard then my short answer is probably no, it is not worth paying double for better quality doors. Like I said, I haven't seen unfinished particle board inside cupboards in a long time. If it is laminated particleboard then it might be worth it. Like The Joinery Store said, laminated interiors are typical. Plywood is not unheard of (and I think it is more common in some other countries) but it would be unusual if you did not specifically request it. Just to be clear, the cupboard has been built and has laminate doors, and you are getting quotes to change the doors? For what reason are you thinking of changing them? What do you want the doors to look like from the outside? Do you want them to match any other doors or features in the room which are timber or poly?