I am going to replace my current 40mm particle type kitchen worktop with 30mm quartz. I am getting this professionally fitted. The new worktop top surface needs to be at the same height as the original to keep it flush with the cooker glass lid, (the cooker cannot be lowered). There are some other reasons that make it desireable to keep the same height as well. I have two options, readjust all of the base units to raise them by 10mm or fix sheets of 10mm ply to the tops of the units to raise the height. The latter is the easiest but the former probably the most obvious and is probably what people will recommend I do. One disadvantage of raising the cabinets is that the old plinths will now have a gap to the cabinet bottoms so will have to be replaced. Just interested in other peoples views on the best thing to do.