A friend very versed in firearms and reloading told me that if you shoot alot stay away from the .257. He said the rifling can get shot out alot easier on a .257 due to the length of rifle twist that is being used. I have never heard this before and cannot confirm the validity. I am not trying to discourage you in making your decision. I would opt for the .25-06 myself. The ammo is more mainstream and far less expensive. If Marlin would ever start volume producing the XL7 in .25-06 you just might save yourself $75. This is my next gun. I am on multiple waiting lists.
My father bought the weatherby vangaurd chambered in the 257 and really loves it.he's a reloader and found a good load for it.i know he uses the barnes x triple shock in 100gr.he shoots 200yrds plus on a regular basis with sub-moa.but he paid alittle more for the sub-moa barrel and it was worth every penny more.