Replacement of under sink cabinet floor
There's really no reason to replace the cabinet floor. I had the same decision to make a number of years ago. My dishwasher hose cracked and leaked water all over my particle board cabinet floor. I cut out the damaged area and was measuring the hole for a replacement piece when I stopped and asked myself "why replace it?" The kitchen tile floor had been extended to the walls so I decided to just cut end pieces to support the existing ends of the cabinet floor and Good Stuffed the seams to bug proof the area. I did get a big plastic tub that fit right in there in case I ever had a leak, but that was it. 

Since then, I've had to replace my faucet and my garbage disposal and the extra 6" of space to work in was really welcome.