So I found my old Anaglyph glasses and tried this out.
The major con is that you lose a lot of color in the scenes and it may take a while for your eyes to adjust. After you find the separation sweet spot in the slider and let yourself adjust, tt feels seriously awesome.
After a good hour of flying around I almost forgot I had these on. My eyes had adjusted to the 3D and to the different coloration. Now with my crappy anaglyph glasses I get some ghosting so I went ahead and ordered some nicer ones online that, according to reviews, have less ghosting. Your mileage may vary.
For anyone considering a Rift in the future, this is a great inexpensive way to see the potential Elite has for 3D gameplay. The devs have made some verrryyy sexy design decisions with this, such as the way the ship's HUD elements float above the dashboard and the way the targeting cursor appears in the distance while other UI elements are more closer to you. Also dat 3D galaxy map... It is all a joy to operate. And just being able to notice the glass surrounding the cockpit when light hits it at just the right angle is really immersive.
However I did notice that while all of the elements inside the cockpit are 3D, nothing beyond it is. That means any objects, ships, stations, or asteroids you approach all appear 2D because they aren't shifted in any sort of way in Anaglyph mode. For those with DKII, is this the case as well or do you really see the depth and size of some of these other objects?