I've got, side by side, a glass and a crystal Glencairn. I'm finding that there is a subtle (yet enormous) difference in the feel and "vibe" of these glasses. The crystal has a slightly softer feel in the hand. Not quite as heavy and minus a bit of the ballast of the glass one. The shape is very slightly different, a bit thinner at the neck. So classy.
If you don't have one, get yourself a crystal Glencairn and you'll instantly know why this glass garners so much affection.