Matt,
I've thought about these nice little boxlocks for upgrades as well. They are functionally a very attractive potential upgrade project. But like Tom says, you're not gonna get anything for your investment later. If you don't care, and can stand more frustration of waiting on craftsman to do the work, go for it. Me? I'm a glutten for punishment. But I do try to pick my projects with some tempering from the wise.
I think, if you shop around, you can find some 4/53's that have very good wood... for a little premium. But, much cheaper than restocking yours if you sell it off and buy the one you like.
But one of the great things about the 4/53 compared to a NID or Parker Repro is generally, the 4/53 will be lighter, in some cases by a full pound.
