Most cv boots fail on the right because most are over the cat convertor and a lot of heat rises and therefore the inside one near the engine goes first, usually. I put a piece of aluminum metal under that boot to protect it from this. There isn't much room to do that, but can be done. These boots had failed when I bought my last two subs.
Clunking can also be caused if the large nut on the axle is not tight. Personally, I don't consider the clunks for a cv joint to be too critical as long as there isn't a split boot. The balls are about three quarter inches in diameter and these joints are way tougher than our U joints. They are very strong and would make a lot of noise and last a long time before total failure. To me, some clunks are part of owning a Subaru with this kind of joint. I admit that all my Subaru's have been used before I got them, so I've learned to deal with some clunks. I'm perfectly capable of replacing the cvjoint axles, but I'm also perfectly capable of keeping an ear on the noises while I'm driving and detecting anything that changes for the worse and dealing with it. I have too many things to keep them all in perfect shape. They all are mechanically sound though.