I have had a few skiers crack their mounting plates, both G10 and aluminum. It can be caused by not having the area firmly attached to the ski, but sometimes skiers pull up a lot with their front toes. If it happens within the first year of use, I usually replace the plate, otherwise I can always rebuild a system for the cost of parts.
The system is designed with the ability to cant/rotate the boots with the same holes that Radar uses for mounting. So I'm not sure why that would be a problem. I have no problem setting up the plates so that the two boots touch if desired, sometimes the size of the boot makes a slightly different hole pattern needed in the boot plates. Since each system is built to order, I can make those adjustments when needed if I have the boots on hand or when requested by the skier.
I am working with a skier who uses the larger boots on some tweaks to the xlong plate to strengthen it. I am always looking for imput on improving the product from users. I can also use a slightly thicker(.025") mounting plate material when needed.
As for adding weight, the double boot system is essentially the same weight as double Tfactor boots. Also any slight added weight directly under your feet makes no more difference than you eating a bigger breakfast before you ski. It is unlikely that the ski would sit significantly lower in the water.
I am always willing to help skiers with any setup or design issues.