I shot both before buying, while the animal you're aiming at will probably never notice the velocity difference between the two barrel lenghts I sure did when it came to muzzle jump, shot recover, and getting back on target for a quick follow up. with the full power (350gr @2150fps chrony'd) loads there was no contest, the longer barrel and pistol grip style grip on the 1895 made it far better ballenced then the 1895G IMHO. after some practice i'm able to control the rifle quite well and spot my hits. doubt I would have had such luck with the little 1895G, although it makes a more attractive package if storage space and packing ability are in question. (although i've never had a problem with my 1895MR in those respects.).
either way, hard to go wrong with a marlin lever gun.