There's nothing wrong with the glass Glencairn, by the way, it's a fantastic little thing.
I have a crystal glass that I bought for cognac that is similar to the Copita glass but I never use it. Never cared for stemware, always makes me feel like I'm at a wedding or someplace I need to wear a tie. I suspect the Glencairn would be a great cognac glass.
It's been said before, but keeping a good variety of glasses on hand will enhance your experience. I go back and forth between a few different styles of glasses, depending on my mood. The best glass is the one that's got whiskey in it.