Im about to order a rebarrel job and have been thinking a lott about the lenght of the new barrel and also asked about it on some Swedish gun forums.
Recently there was a test in a Swedish hunting magazine where the conclusion was that a short barreld 300wm (in this case a Browning Bar I belive) was nothing more than a 30-06 on high octane, the gain of the magnum round was considerd to little for the added recoil, muzzle flip and muzzle blast.
A shorter barrel is stiffer but at the same time, I got a magnum rifle just because I wanted it to be a magnum, not a 30-06 on a boost. :-)
Im looking at a Lothar Walther #2200 in 26", 27" or 28" my selfe, 27" seems like a good compromise between speed loss and handines/portability of the rifle.