As I said: This will not increase the load on the RAM chips at all, or damage them, or make them wear out faster. RAM isn't like an LCD monitor where locking an image into place "burns it in". If the X server weren't locked into memory, then it would just be some other piece of data filling that space. There's no such thing (for all practical intents and purposes) as an "empty" memory block, you don't "turn off" memory like you do a monitor, and it doesn't harm your RAM to have part of the memory space permanently dedicated to a single process.

What it will do, however, is change the profile of the swap (i.e. flash memory) usage. The X server, which would otherwise occasionally eat up write/erase cycles by swapping out, will no longer cause any flash wear. Other processes on the system, however, will be somewhat more likely to swap out because they can't use the memory that is reserved for X, so they will cause slightly more flash wear. It's a balance, and I have no real numbers on how it might affect flash usage overall, but my intuition is that, since the X server is used so much, it would probably result in an overall decrease in flash memory usage.