The Krag Jorgensen Rifle (U.S. Magazine Rifle, .30 Caliber, Model of 1892/1896/1898) was exactly what the Ordnance Department wanted. Over 50 rifles were looked at by a Board in 1892. The clip fed Mauser was one of the rifles considered. The Krag was selected even over this rifle due to fear of soldiers wasting ammo by getting too many shots off. Some older Army officers still preferred the Springfield Trapdoor over the Krag. The Krag has a magazine cut-off, allowing it to be single loaded with 5 rounds in reserve when things got hot.

Losses were great among the U.S. troops, as you stated due to charging up hill. But it was recognized that the Mauser was loaded quicker giving the Spaniards greater firepower by fewer troops who had better cover. But the best I have found looking at period articles, the U.S. troops were proud of and fond of their rifle. The Krag is a well built and accurate weapon, even though the design may have been somewhat outclassed by the Mauser that also used a more powerful cartridge. The next service rifle in 1903 was based on the Mauser design leading to a $1 royalty to Paul Mauser for every 1903 Springfield rifle built limited to a $200,000 payment.

Much experience was obtained during the period that the  Krag was the main service rifle. It was a major step for the U.S. into the smokeless powder, magazine rifle era. Some say that it was obsolete as soon as being adopted. Still, the U.S. had a good showing at the time that the Krag was the main service rifle as it was becoming a world power.

Well, that's my rant in a nutshell.