Maybe a good Idea, maybe not, depending on what you're doing with the gun that takes that kind of ammo.
If you have a wheel gun for self defense, basically, you have 5 or 6 rounds to get you out of trouble. That's why most law enforcement and people who have to depend on their handgun went to semi-autos . . they have another 13-16 rounds on hand very quickly in a second magazine.
However, if you, as a civilian, need more than 5 or 6 rounds in any kind of situation, you either needed to learn to be proficient with the gun you're using or you're in a gunfight you shouldn't have gotten into . . Should've taken a rifle (or a Shotgun) to the fight.
Which brings me to another observation. The Shooter in Colorado was a nerd, which, I'm sure, saved a lot of lives in that theatre that night. He opted for a high Cap "Drum Magazine" for his AR . . All that "handy" sh*t doesn't work. If it did, you'd see drum mags on all of the military weaponry. The straighter the feed, the more reliable. High capacity and quick reloading won't replace accuracy with any firearm, which usually separates the men from the boys when the sh*t hits the fan . .
Hot tip, Ruger LM 9mm w/ laser sight. 6 rounds where you want 'em, when you need 'em! Little bitty sucker but easy to shoot, fills the hand . . or the pocket . .