I've just done that, i.e. treating my tan Addison 1,000 Miles with Obenauf LP. They did in fact get darker, from the kind of yellowish colour they had in the beginning to a mahogany/tobacco like colour, which I like, though.
I've just done it now. The colour might again be a bit different tomorrow after the LP has been soaked up properly.
By the way my tan Addison ordered via Crane's don't have any empty stitching holes. Not a big deal to me anyways, but still nice to see.
If you could snap a picture or two of them tomorrow I would really appreciate it.