i bought a guide gun 2 years ago in 45/70. i LOVE it also. you couldn't pick a better gun to fall in love with.
i have not had the oppertunity to kill anything with it yet. i hunt whitetail, and i put in for an elk permit this year. but to be totally honest, elk may be more than I can chew. i am disabled, so i have to hunt pretty close to my 4x4 gmc jimmy. that limits a lot of where i can hunt. i can go quite a distance, 50 yards at a time, but i HAVE to be able to drive the jimmy to where ever the deer drops.
one of the reasons i decided on the 45/70 is the ABSOLOUTE drop dead factor. i am a fairly good shot, so i can place a good shot almost every time (nobody is perfect). the furthest i have ever had to chase a deer (prior to becoming disabled) that I shot was about 75 yards, and that was a deer that i shot with my .357 magnum.
now, you have many decisions. you have to decide wheather you want a straight stock (guide gun or cowboy model) or the curved pistol grip ( xlr< which also happens to be stainless steel). in shooting, both function the same, so it is purely asthetics. then, you will also have to consider barrel length and shot capacity. the cowboy model holds way more than the guide gun (which means that it will also be way heavier). but you may want to consider this, some states have a legal limit as to how many rounds your gun can hold when deer hunting (michigan does!) so if you buy a cowboy model, you may have to put a plug in it.
anyway you go, you will not be disapointed. but one thing, they DO KICK! i would say it is at least that of my 300 win mag. and the gun is light. for me, the gun wants to jump out of my hands. i am seriously thinking on having a muzzle brake installed on this gun!
by the way, when you buy ammo, don't pass over the HORNADY LEVEREVELOUTION ammo! it markedly improves the aerodynamics of the bullet, which means extended yardage with NO extra recoil! and the bullets come from the BEST name in bullets, PERIOD, so you know they will function properly. if you plan to go for bear, or elk, i would use the buffalo bore +P 400 (or heavier) grain bullets, thay will perform better on that sized game. unless you load your own.
these are a reloaders dream! they can be loaded way hotter than what most ammo makers have to load their ammo for, as they have to be certain that the loads they supply can be shot in the OLD, WEAKER trapdoor guns. THIS ACTION IS QUITE STRONG, and can take quite a bit more pressure than the old trapdoor models. just use your head, and follow the loading reccomendations for this gun and you will be fine.
good luck on your decision, and start enjoying!