Following and enquiry by Tony Sheeky of Halifax P.S.
The reason that the YPU have made this decision is purely administrative. For the PAGB Annual Inter-Federation Competition and Exhibition we are now required to submit images at 1600×1200. If the YPU continued requiring 1400×1050 we would have the problem of having to ask all authors of images selected for the PAGB Inter-Federation submission to re-submit their images at 1600×1200, a task that I would not wish to perform.
The PAGB projector is 1920×1200 but the PAGB decided to continue with the aspect ratio of 4:3 and so chose 1600×1200 as the standard to adopt.
I am not aware what the aspect ratio is of your projector is but as it will operate at resolutions higher than those now being adopted I assume the resolution is 1920×1200. The PAGB is able to select the Canon projector it uses to run at 1600×1200 and ignore the remaining pixels to the right and left. It is also possible to have the projector remain set at 1920×1200 and when presenting images at 1600×1200 the system only uses the centre 1600×1200 pixels without problem. This method is also dependant on the programme being used for projection and the PAGB ensures the programmes used will do this. The PAGB uses Bridge or the competition software developed by Adrian Lines of the L&CPU for projection at their events.
There are some clubs who still use 1024×768 which is the resolution originally adopted by the YPU and PAGB. This was then replaced by 1440×1050 which has now been upgraded to 1600×1200.