When you say "over time", that seems very vague. Even lacquer will wear down over time.
I spoke with a very experienced refinisher who does a lot of tru-oil necks (hundreds) and he tells me that it's a very nice finish. He has not had any issues with the finish so far.
Here is a pic of a neck, on a guitar he plays very frequently, that he tru-oil'd four years ago:
In any case, my point is only that it is a much more durable/protective finish than traditional oils, and can get quite hard if allowed to cure properly. A tru-oil finish, done right, will protect maple from discoloring just like laquer will.
Here is an interesting thread I found about tru-oil that touches on issues we are discussing such as durability and hardness: http://www.kitguitarsforum.com/forum/threa...?id=357_0_7_0_C
CMA