After careful deliberation, I've done this twice. After deciding that I personally can't hit anything with Glocks (for whatever reason, personal to me), I traded off both that I owned. One for a Kimber Custom, the other for a Colt lawman. I don't regret either transaction. I love the Kimber, and although I personally don't care for the way the Colt feels or shoots, it is inherently a much nicer gun that the Glock. 50 years from now, there is a good chance we will be awash with high grade gen 2 glock 17's, while I doubt the same will be true for 98% blued colt revolvers (even the non-python grades).
However, I don't think I have any other items I would consider trading. Even my Ruger P91DC. Its ugly, coarse and generally unremarkable. However, it is perfectly functional, shoots reasonably well and is my only .40cal. I'm happy to keep it simply for its functionality.