When I built one of my rifles, I debated on whether I wanted a .257R / .25-06 or if I wanted a 6.5 Swede. The calibers are only 0.007" different in diameter...but bullet selection (even 10 years ago) heavily favored the 6.5mm. This trend will likely continue for the foreseeable future.
I decided to go Swede and initially loaded it with 100gr bullets (Partition, NBT, Hdy SP) at about 3000fps to essentially duplicate the Roberts. In my Looney mind, I rationalized that this was a better version of the Roberts with the ability to load heavier weight bullets if I hunted anything other than close range whitetails.
My wife and I ended up taking probably about a dozen deer with the 100gr Hdy SP before my ADD kicked in and I started playing with other bullets. While the Hdy SP is now discontinued, I wouldn't hesitate to use the 100gr Partition in the same capacity for just about any deer hunting east of the MS River.
I guess my point is that the Swede is probably the more practical cartridge choice in this situation based on some of your points as well as the ability to essentially duplicate Roberts level performance if you so choose.
