This discussion only reminds me why the only "1 caliber handgun/rifle combination" I have is in .22lr.
Doc - I thought you were right on track there for a minute - but then you diverged. As JOG stated, the only reason I see for such a set is for the purpose of using one load. With all the centerfire rounds, you either have to load up for the rifle or down for the handgun to make it truly optimum for most people.
If it were me - I might prefer to go with a .44mag. I don't see any reason to subject myself to full-power .44mag loads in an easily-carried revolver if I also have with me a rifle, so I would load down for that. Now I have two loads that must be kept separate. If I were to go with .357, it would be the opposite. I have no problem at all with full-power .357 loads, but I might want a little more oomph to justify carrying the rifle. Separate loads again...I think that's cheating the concept.
If I have to load differently for the different guns, I'm gonna go with my best handgun fit for the mission, and a preferred rifle. In 99% of the backwoods excursions I've ever done or am likely to do (unless maybe I get lucky enough to hunt Brown Bear in Alaska) I could be happy as a clam with any of the major-caliber handguns (.45acp, .357mag, .41mag, .44mag, .45 Colt) and a .308win or 30.06, or whatever fits the occasion (lately for me - a .243).
Small-game hunting is another story. There, I really prefer to take game with a .22lr handgun when I can get close enough - but I often bring the .22 rifle along, in case conditions force longer distance shots.
OTOH - and thinking out loud here....
If you look at it that way - I mean not as a matter of power gained, but more of a range and ability to aim issue - then a "normal" max-loaded .357 starts to look pretty good. Carried in a medium-frame 4" revolver, it is a very useful tool. Put that same load in a rifle, and my reliable range increases two or threefold - with still enough power to do terminally what I could have done with the handgun close-up.
If we're talking about urban life pistol/rifle combos (and I think we're not), it's a whole 'nuther story.
