What is the width of real estate that you've got to put in the display screens? That, along with which units you decide on going with are going to be the biggest issues as your Raymarine E127, while being a 12" display, is actually almost 14" wide overall. So, putting two of those in there as opposed to another smaller 12" display, like the Garmin 8612xsv for example at only 11.9" wide, is going to make for a rather large difference at over 2" each. I'd make up a cardboard cutout for the dimensions of whichever displays you want to use and then go from there to see if it'll fit.