Kodiak, sorry took so long to get back.
Past history first. 444 is a short sale, it isn't what is says it is -- its NOT 44 cal anything! It is .429 bore size whereas the 450 Marlin and 45-70 are .458 bore size, thus you get the full selection of .458 bullets out there which is huge! As THS78 pointed out 444 bullets tend toward the small side and the .429 bore size is the reason why. Don't fall in love with the ballistics chart, remember what I consider to be the operative word in your first post: g-r-i-z-z-l-y! The attacks are usually lightening fast! You need slap down power not a velocity/energy discussion! Go with the caliber that gives you flexibility in both bullet weight and quality offerings. The .458 bore size has all sorts of African connections; 450 Marlin or 45-70 is the better way to go. As a tie breaker call up a major gun shop in Anchorage or Fairbanks, Alaska and ask them which caliber they're selling most of for new Marlin Guide Guns! (I love Colorado, but ALASKA IS THE REAL DEAL - WHOLE DIFFERENT BALL GAME!)

Regarding pistols, its a lose-lose on that one, if its not fairly mean and nasty to shoot when you are shooting targets, then its not much of a back up weapon for big game: consider 44 mag and shoot 44 specials except when you are serious. If the 45 you are talking about is a 45 Long Colt then that can be a worthy back up (to a big game rifle). If you are talking 45 Auto I'd leave it at home, big bullet but dinky case. When big game hunting, pistol weight is just too much of an enemy and using the typical holster set up, the weight's going to be uneven and at odds with your pack and if you keep it in your pack - what use will it be? Carry 5 more rounds of heavy bore rifle rounds, have a back up rifle in camp and don't stray too far from your hunting partner - there all the bases are covered and you've saved $500.
EKM

Good judgement comes from bad experience! Half of elk hunting is knowing what NOT to do!